O_O Why that is (assuming that you're correct), I won't understand. FE6 is one of my least favorite games in the series with its unbalanced weapons, mostly mediocre characters, and bad aesthetics even for the GBA. But it's opinion so whatever.
Being lots of other people have different tastes than you. I actually formally imported (READ: DID NOT PIRATE) the Japan-only games in the series, and FE6 is among my two favorite games in the series (the other being FE5). I actually wrote the most detailed review for FE5 over at GameFAQs.
What's wrong with middle of the road? Considering that Ike and Marth are skewed on opposite sides of a power-speed continuum, happy medium would round it out nicely. And Chrom can still have a style unique from the other two.
Because that is literally quite boring. There is already characters like Link who are a more well-rounded type of swordsmen. And then you have characters like Shulk or Isaac who will likely get into Smash 4 as well-rounded swordsmen like characters, while also bringing in the unique attributes of the Monado (Shulk) or Psynergy (Isaac) for their respective movesets.
Which speaks volumes for the importance of international characters.
No, it shows Sakurai does not mind putting in international characters if he knows that they will be received well amongst overseas Smash Bros. fans. When a Japanese Smash Bros. fan asked Sakurai whether he would put in more Japan-only characters in Brawl (this was with the pre-Brawl journal), Sakurai gave told a story about a black man that personally thanked Sakurai for including Roy in Melee. Sakurai used this example to say that Japan-only characters have the potential to be well-received all over the world.
It still doesn't change that most people who love him don't know anything about Fire Emblem.
It does not matter. Popularity is popularity. Fire Emblem is a niche series in the West, and in Japan, Roy is plenty popular among FE fans anyway.
Besides, if you are going to say "Roy's popularity is not legitimate because many of his fans have never played FE" you might as well expand that argument to Marth, Ike, Ness, Captain Falcon, Lucas, Ice Climbers, and ROB, of which few people have also played their source material games. For characters like Ice Climbers and ROB in particular, they have subpar source material games.
For a character like Captain Falcon, whom is hardly ever seen outside his vehicle in his games (with the exception of GX), could you fault someone for liking him solely for how he is in Smash Bros. without ever having played a F-Zero game?
As a matter of fact, Roy actually brought many people to even try out Fire Emblem in the first place (including myself). So is very insulting to say that fans of Roy are not legitimate just because they have not played FE6 (which was never given a proper international release), or any other Smash Bros. character for that matter.
As it stands, anyone can love a character in Smash Bros. and still be a fan of them, and that makes them no less legitimate as fans.
Look also at Waluigi/Toad. They typically are no less important than the rest of the Mario cast roster in the spinoff games (although Toad has made several playable appearances in the Mario platformers lately), yet, I doubt you would call the fans of them any less legitimate.
See my above comment about the costume clone argument.
Costume clones are a horrible idea for most characters in general. They would only be well-received for a select few such as Dark Pit or Dr. Mario.
Does Roy bring much to the table?
Yes he does. He brought many people to Fire Emblem, and it was his very high popularity in Melee (along with Marth) that convinced Nintendo to bring the series over to the West.
As I said before, Roy's Sword of Seals could at the very least make him stand out more than Chrom. It has a long distance attack and can heal the wielder. Not to mention aesthetically the fire properties of it help it stand out relative to other blades in the Smash Bros. series.
There have been a slew of ideas on what can be done with Roy to make him an interesting and worthy character addition solely looking at the moveset perspective. Habanero for example posted something particularly inventive.
A single special is better than nothing. And if Sakurai wants people to know that FE is more than blue sword guys, assist trophies and other things can do that.
People have more exposure to characters than any other content. As a character, Chrom simply does not offer much, and a single-special is not "better than nothing" when Roy potentially offers several unique specials just based off the canonical abilities for the Sword of Seals alone.
And for other potential sword-user newcomers (Takamaru, Shulk, and Isaac) they all have attributes to them that make them distinctly stick out relative to the rest of the cast.
So, a promotional stunt for the series and its upcoming game at time of Melee's development and release.
So you just ignored what I wrote about why Sakurai included Roy, and just said "la la la just an advertisement"?
Which is why costume cloning is too good of an opportunity to pass up. Besides, Waluigi is wanted in Japan and scores highly here (for some reason), but he's still a terrible choice. My point is, popularity alone doesn't carry a character.
Mario characters in general are not highly wanted in Japan, so I don't know where you heard that from. Secondly, there is a slew of Mario characters in general that are highly wanted (Bowser Jr., Paper Mario, Toad) yet also have more importance to the series than Waluigi.
Roy not only has popularity, but he has veteran status in Smash Bros., and was the main lord of the pivotal game to the Elibe arc in Japan (which one of the most popular arcs overall for the FE series).
Already addressed Robin. Lucina isn't the main protagonist of Awakening. Anna is a shopkeeper and doesn't have an important role in any of her appearances.
Reading comprehension. I was saying that Chrom looked so un-appetizing as a possible newcomer, that people have looked to Anna, Lucina, and My Unit as altnernatives. How likely they actually are is another story.
Pokémon and Fire Emblem are two very different animals. With Pokémon, it's about reserving a slot for the most recent generation and the most popular feasible Pokémon for that generation. So in Brawl, that was Lucario.
In Melee, there was not even going to be a "newest" rep. Sakurai was originally going to have Melee's non-clone roster plus King Dedede, but Sakurai felt that six clones would be received better than one more original character.
That's because Animal Crossing is not a fighting series, none of the characters have moveset potential, and they aren't fighters in any way, shape, or form.
There is a lot of people that would disagree with you on that, however, it is an example that shows that extensive content can be given to a game or series without having to grant it a playable character.
Already addressed that. Awakening is the most recent title, among the most critically acclaimed, had the strongest first sales month, and will likely be the first FE to sell more than 1 million. (Does anybody know of a reliable sales source?)
It may be the most recent title, but its certainly not the most critically acclaimed. Secondly, as others have said, sales don't matter for FE, otherwise Ike would never have gotten in.
My arguments would just get repetitive at this point. I don't think Roy's important enough, popularity alone doesn't suffice, costume clones, etc.
FE6 was the main game to the Elibe arc (FE7 was overall a smaller scale story and setting the stage for FE6 to take place, much like FE5 was a sidestory overall to FE4). Roy was basically the savior for Elibe and helped bring peace to the continent in a massive conflict that invoked the ancient dragons and the superpowers of the continent. Overall, Roy is still the most popular and iconic lord from the GBA trilogy.
There is also even an interest by Intelligent Systems to remake Roy's game some day (which will probably happen if Roy returns for Smash 4).
What does Roy being to the table though?
Overall, even with all his popularity, I just don't think he's an important enough character. Awakening's popularity and recency demand that it gets a playable character. The costume cloning is just too good of an opportunity to pass up. I think I've said my piece.
I have already argued why Roy is important to the series. However, aside from Marth, its very subjective in general to argue which lords are more important than others (outside a few like Leaf and Lyn who are more sidestory heroes).
Secondly, FE13 could perfectly be represented with stuff aside from playable characters.
Lastly, why can't we get both Roy and a FE13 character. Roy on his own certainly has the merits to return. There is nothing nowhere that says just because Roy returns, a FE13 character will have to be left out.