Why does it matter if it's pointless? Isn't having a second set of Wario costumes pointless? Is there something so wrong with having polish in a game? Dry Bowser isn't affecting anything else or keeping other stuff from being in the game. Why do you get to say what's pointless and what's not? I guess it's pointless to have Alph's ship in the background of the Pikmin stage if it doesn't do anything.
1 - It matters if it's pointless because it does take up development time, albeit less than it does for another character like Zero Suit Samus, but it still takes development time.
2 - Having Wario having two costumes isn't pointless, Wario is well known for two things. The WarioWare franchise (which can be considered where most of his current fanbase is from) and the Wario Land franchise (this sort of includes his Mario appearances too). For a character like Wario to be popular for two very different things, it would make sense to attempt to please both of his fanbases to allow you to play as the Wario from those specific games (Wario should be given some moveset changes to help represent Wario Land more though).
3 - I never said Dry Bowser in general is a bad idea, I just said the way you want to implement it is a pointless waste of development time. Why would I want to go through the time to play as Dry Bowser (with nothing unique from Bowser other than appearance which is what you're suggesting) when I could just potentially unlock him as an alternate costume and just play as him through that? If it actually did something, like perhaps make Bowser become Dry Bowser during the Final Smash have him attack as it, then that would be a different situation. But it's just something completely aesthetic that would just be pointless in the long run.
Sort of how the visible battle damage concept was in Brawl. Sure it could have been cool, but what would the game have been any different with it?
4 - Drake has nothing to do with the type of discussion we're having. It's got nothing to do with characters in the slightest, it's a background object. It's not meant to interfere or be part of the actual battle going on in the foreground.
I don't see people complaining about a Doctor Mario Costume. Dry Bowser doesn't have to be a Sheik thing or a Zero Suit Samus thing. Bowser often becomes Dry Bowser during fights, so I suggested it's quite possible there may be some sort of mechanic where Bowser can become Dry Bowser either through fighting or something else. Not everything in Smash has to serve this giant frikin purpose that affects everything around them.
5 - That's because Dr. Mario exclusively being an alternate costume of Mario makes sense.
6 - You're the person who suggested that though, but with the change being completely aesthetic. Which is why many people said, "Why not just make Dry Bowser an alternate costume then?".
7 - For the most part, everything should serve a purpose in the game because why would you want the people working on the game to make something that serves no purpose in the long run and waste their time?
Dry Bowser is not a new character at all, it's a change in looks. It's no worse if not less pointless than having a second set of Wario Costumes. Should Villager not have a girl set of costumes, would that be pointless too? It doesn't do anything, it's not like girls are really gonna care that much.
8 - It's pointless for the player to have go through a certain process in the game (like through final smash) to do become a character with no changes other that appearance. I mean if it was something like, "Get covered in Lava in Norfair and come out as Dry Bowser for the remainder of your stock" that would be a cool way to unlock the Dry Bowser alternate costume. But I wouldn't want to have to go through the trouble of doing this "Special way Bowser can become Dry Bowser" if I could just pick Dry Bowser before the round begins and play as that from the start. Alternate costumes are a great way to make people to still want to play the game after getting all of the characters.
You know what I think is pointless, Mewtwo becoming the awakened form as Sheik or Zero Suit Samus do. Whatever abilities he has are either going to be more powerful or not different enough to make it worth swapping or programming. The Awakened form should be it's own character.
9 - It's not pointless and it would be a waste of a character spot to make it's own thing, especially because it would already know every move Mewtwo would know because that is how forms work in the Pokemon games (unless you're Keldeo and you need to know a specific move in order to become this new form, which doesn't seem to be the case for Mewtwo). Why would Sakurai ignore the ability to create a new unique character whilst bringing back the universally most requested character to be added into Smash Brothers? I would love to see the ability so change up your stats to turn Mewtwo into an entirely different character whilst having the same moves. This would pretty much be giving Mewtwo a clone character that doesn't end up taking a slot.
Besides, wouldn't that basically be what you want to happen but with it taking up another character slot?