No, Bandana Dee is way ahead of any other Kirby character. Sakurai made the ****ing character, if he can find potential in Pit (all he did in his games before Brawl was shoot arrows), he can make Bandana Dee work. Roy is technically a semi-clone now.
Vince can work and if you're talking about how its out of character, I think you might want to talk with Ganondorf, ROB, Villager, Wii Fit Trainer, and Captain Falcon. Ganondorf is still a ****ing semi-clone of Falcon, ROB didn't fight in his game, Animal Crossing is a very peaceful franchise and Villager fighting is technically out of character, Wii Fit Trainer isn't making you healthier by literally beating the **** out of you, and Falcon's never stepped out of his car to do a Falcon Punch.
Those characters all represent the gameplay of the game they come from. Falcon is fast and deadly, and has falcon punches that represent the movement you can do in F-Zero X double tapping the L and R triggers to destroy other cars. The same applies to Starfox, the moveset emulates the gameplay.
Ganondorf has a random moveset, but it's not out of character: he is a secondary character so he doesn't need to represent the main gameplay of the game, but he does represent very well the king of evil he is.
Everything makes sense, WiiFit Trainer still does yoga.
If you make Vince fight, doesn't make much sense, since it doesn't represent in any way the gameplay of the game. The gameplay of the game consists in creating art, not destroying art into other people to defeat them. Vince loves art and respects it, at the same time he's a very calm old man, and you would expect everything but a fight from him.
You can do it, but it would be unfitting, or at least this is what I think.
The only "offensive" or "destructive" action that you can do in Art Academy is ereasing a part of your drawing; even Animal Crossing has offensive actions into his gameplay, traps, sling, destroying trees, etc; Art Academy doesn't have any of those.
Also, about Bandana Dee, Sakurai didn't made the character, he just put a bandana on a waddle dee for a minigame, and in the minigames of Kirby Superstar almost every character/regular enemy had some costumes, for example that wheely with the samurai hat, or Dedede with a kimono.
We won't know the result of the ballot until october (or we won't ever know it), we only know that the Bandana Dee fanbase is very noisy, this doesn't mean that other characters doesn't have a fanbase, and at the same time it doesn't guarantee him a place in the roster; People requested Toad for years but he never felt like putting him in the roster, despite being a recurring and main character of the Mario series. There are many supporters of Bandana Dee, but there are also many people who think that he's generic and who hates him, so he would be a character that would generate lots of debates; it's by no way confirmed to be the next Kirby newcomer. There are many characters with lots of requests, none of them are excluded, none of them are confirmed.
And as I already said, it's very possible that Kirby will get more than just one single newcomer as well, since the series has been overlooked so much.