That's not really what I'm saying. I think surprise is fun for sure, but the reason I say I think it would be "healthy" is that it would allow for a consideration of more characters designed to fit unique gameplay archetypes as opposed to the other way around, moulding popular characters to match certain archetypes. Smash has done both multiple times, but you can see even recently Isabelle for example got in primarily on the basis of her being Isabelle and her gameplay of "oh she's a variant of Villager" was designed to match that (no shade on Isabelle, I think she's fun, that's just a fresh example).
When I say "MVC-style picks", I don't fully mean "haha cutting Wolverine so you can add Jedah", I mean in the sense that for example with the Street Fighter roster of each game, the characters tend to be Ryu and Chun-Li as the vital picks, and then multiple wildcards built around either just popularity or how interesting they would be. It doesn't go adding Ryu and then adding Chun and then adding Akuma and then adding Ken or such, just going in order of iconicity, it goes adding Ryu and Chun and Akuma, and then going for like C. Viper because she's a fresh face and is distinct as being a set-up based weapons fighter. Even Akuma gets in on a mix of his popularity and also his gameplay archetype.
Again, Smash has done this before intermittently, a clear would probably be for example Incineroar getting in over more marketed faces because he had an interesting angle for his moveset and fit a unique archetype, or Rosalina being higher priority than Bowser Jr likely because Smash had no puppet fighters, and is pretty good at adding fresh faces, but I think it would also be difficult to deny that plenty of choices definitely don't go for that route either. Like Sakurai has said, he adds characters he thinks he can come up with an interesting concept for, but certain things have a bigger spark than others for sure. End of the day something like MVC is a traditional fighting game with different obligations to Smash, like I said already there's a million reasons Nintendo would never do this and I wouldn't expect it to be broadly well-received depending on how something like that were to be handled, I just think a shake-up like that would allow for a lot of interesting new archetypes and exploration of the gameplay and result in a fresh face. There's a balance between characters as functions and characters as characters basically, and I think you can land a balance there in an ideal world to get something interesting and something I personally would like as a direction.