On one hand, yeah, it can ruin a character because it gets boring to see them constantly using the same move.
On the other hand, I don't think it ruins a character: people are just looking for the essential moves, the signature style, and the character's appearance, and having few moves can even make the game easier. For me, having a balanced AI is more important, which is why I uploaded KidBuuZ2 here: a character with only 3 buttons to use and few moves, but a lot of people love it as it is"KidBuu," and it has a really strong AI.
BUT EVERYONE HAS THEIR OWN TASTES AND OPINIONS