Honestly, it's because most of the people whom use the Lucina boards aren't so much concerned with Lucina in Smash as much as they are concerned with Lucina the character. Most Lucina mains aren't tournament goers and actually just play the game casually.
Very little competitive discussion actually takes place here. If you look at the Lucina boards you'll realize just how many threads there are dedicated to fan art, asking people what they personally like about Lucina, and why people generally consider Lucina one of the works characters in the game. There also isn't just one of each of those either. There's about three of each the last time I checked, which shows me that a lot of people just want to post about their waifu. That's fine and all, but that's what the social threads exist for. At least for the fan-art threads there could be at least one giant one where people could post. I guess it doesn't matter since I'm sure mods clean up and delete a bunch of them, but it still goes to show the general mentality of what is at least the most vocal portion of the Lucina boards. *cough* no thread or discussion dedicated to her changes in the recent patch *cough*
Don't even get me started on the whole Lucina vs Marth debates that happen here. There has been a total of three massive threads dedicated to just this alone (which goes to show that people aren't checking what has been posted already, hence three art threads at one point) When someone asks why Lucina is generally considered a bad character the discussion inevitably turns into a comparison of the two. People will respond with points in Marth's favour that obviously make him a better character, but the back-and-forth that comes from the Lucina advocates basically boils down too "I don't want to space". The thread then inevitably descends into a Lucina circle-jerk and how she's bae. They asked why people though Lucina was a bad character and inferior to Marth so we told them, and then they say that we're being mean and elitist. At that point we just sort of abandon the thread because it's going nowhere and we've said our pieces.
My phrasing and explanations here have been a little-mean spirited, but at this point there's just no beating around the bush. Just look at this thread here, it's exactly what I was describing above:
Evidence.zip:
http://smashboards.com/threads/is-lucina-really-that-bad.409671/
I think what happens is when people say Lucina is a bad character in Smash I think some people equate it as Lucina is a bad
character. Obviously a characters viability in Smash Bros. isn't any indication of their actual character (hello Samus) but there is to be no slander of any sort against the ultimate waifu apparently.
Meanwhile, if you look at the Marth boards you'll realize the huge difference in mentality. There is a much greater variety of threads and every one is dedicated to competitive discussion in one way or another, the video archive is updated consistently, and while the match-up thread has slowed down it still chugs along. There have been great strides in Marth's meta because of this.
This is because Smashboards is a website mostly dedicated to the competitive aspect of Smash Brothers. Lucina is to Marth what Pichu was to Pikachu in Melee. Why pick the worse character when you can play one whom functions the same way with superior options?
Since Marth and Lucina fundamentally play the same, I know Lucina players whom will frequent the Marth boards for information since the Lucina boards are so dry.
I'm mostly just sick of having these same discussions with brick walls over and over again and just wanted to get it all off my chest. At this point I've learned that if someone wants to say Lucina is better because they don't have to worry about spacing, I should just leave them be since I'd be wasting my breath.
The lack of actual competitive discussion on the Lucina boards has been noted by quite a few people. One of my friends refers to this place as Deviant Art for a reason. To be fair though, it has gotten better recently.
I hate to say this because I was a heavy Lucina player and defender before this patch, but Lucina is pretty much a handicap character at this point/ I know this sounds harsh, but Lucina has not only lost badly with this patch, she simply no longer feels rewarding to play.
I also play as Ganondorf and Dr. Mario, two characters widely held as being inferior versions of other characters on the roster. But the thing is, both have their perks that make them rewarding to play. Nothing feels more awesome then just unleashing Ganondorf's power and simply beating down opponents, especially if you nail a Warlock Punch. Ganondorf''s sheer power is his draw in contrast to the combo, dash grab playstyle of Captain Falcon.
Dr. Mario has the appeal of bringing back Mario's Melee-Style moveset. He feels rewarding to play as a general purpose character who can be the bane of Projectile oriented characters like Samus and Villager.
My point is this, despite their flaws, both Ganondorf and Dr. Mario are viable characters, that offer something different from their counterparts.
Lucina's biggest issue is that from the start, she's been in the shadow of Marth. They both share a common moveset, their stats are pretty much the same, their customs are the same and despite them both having fundamental differences in how they play, Lucina and Marth share common changes in each patch.
Which results in the negative of her falling behind her fellow Fire Emblem reps. Ike, Robin, and Marth have both benefited from the changes they have gotten in the patches. Ike went from a lower middle tier character to someone who is on the outer fringes of high tier. Robin and Marth are both middle tier characters now, with major buffs that make them viable.
But poor Lucina has been left to rot in the lowest tiers, simply because Sakurai and his team refuse to address her issues separately. A buff that helps Marth does not translate to improvements to Lucina.
Perhaps worst of all, the Shield Breaker nerf hurts Lucina more then it does Marth.
Now, Lucina might still find her niche and appeal to people who want to use Marth's moveset without worrying about tippers were it not for Roy.
If any character is a blow to Lucina's viability, it is Roy. Simply put, Roy is everything Lucina is not. He's fast, has numerous setups into combos, has insane killing power, and can space much better then she can. Roy's sweetspot at the center of the his blade translates well to being more aggressive then Marth, without the drawbacks Lucina suffers from.
Roy is widely considered not only the best Fire Emblem character in the roster, but to many top-level players, the best Swordsman in the game. He is the perfect character for people who want to play with a Marth-style moveset, without having to worry about the tipper(and to be honest, the sweetspot of the center of the blade can feel just as natural)
I hate to say this, but I'm not sure if I'll keep playing as Lucina. It's not even the fact that I'm using a low-tier character that bugs me. I was a dedicated Ganondorf player in Brawl, and I loving playing as Charizard in Smash 4.
No, what bothers me about Lucina is that every patch reinforces the notion that she's nothing more then an inferior Marth and Roy. Even if she gets buffs from the patches, Marth still gets more benefits at the end.
I just don't know what to say. All the other characters that I use feel like they got something out of this patch, or at worst, are about the same.
Lucina is the only one who just feels worse off in the end. And she just feels pointless to even play unless you really like Lucina for her character from Awakening. In terms of gameplay, she can't get out of the shadow of Marth and Roy.