BanDee to me is on a tier of "wanted Smash characters" on the same level as Toad and Waluigi; People insist they're needed for Smash because they're the "fourth most important character" when most of their appearances boil down to the games that usually feature a trio of characters needing a fourth for the multiplayer mode. It gives the impression to me at least that people want Bandana Waddle Dee not for his own qualities but to satiate their OCD by putting in a fourth slot in a otherwise perfectly complete triad.
Basically I'm apathetic towards them because they're roster filler to me, but I wouldn't despise them if they got in.
I mean, it'd be pretty darn cool if the Kirby franchise could get at least one more character within the span of two entries and a decade+ worth of Smash.
Bandana Dee has even made his mark on the franchise long before he became "Player 4" and obtained his core weapon of choice, which is something that hasn't even been touched on in Smash all that much. Even then, his still has more a personal arsenal to pull from beyond basic Spear-Based attacks and the Spear itself. Not to mention that, as the sole representative for Waddle Dee kind, he would represent a species that has been with the Kirby franchise since the very beginning.
Heck, since he made more of a mark on Modern Kirby (with a stellar attendance since KRTDL) he would probably bring more Modern Kirby content into Smash than the already represented Classic, Adventure, and Super Star games.
I'm honestly pretty tired of people talking down on Bandana Dee fans for not picking "cooler" characters like Marx, Adeleine, or Magolor (even though we can like more than one character) when it's pretty clear that we want him for several reasons, more or less depending on the fan.
I think I can speak on behalf of most if not all Bandana Dee fans, along with fans of other characters who are ridiculed for wanting a character who "isn't good enough" according to some portions of the Smash community.