After thinking a bit, I don't have a problem with Kid Icarus getting loads of stuff, but it becomes a little upsetting when other series get shafted in terms of content. As a Kid Icarus and Fire Emblem fan, I'm happy for the attention the series got on this game, thanks to the release of Uprising and Awakening, but I can't help but think: why can't other fans get as much goodness from the series they like?
I may not be a fan of those three series, but Donkey Kong, Star Fox and Metroid only getting Melee stages in Smash 3DS is a load of bull****, especially when series like EarthBound and F-Zero get new stages. Donkey Kong not having an Assist Trophy is pretty jarring too, especially when EarthBound got a new one and Zelda and Metroid get a few more.
One of the few Metroid games I've played was a Metroid Prime Hunters and I was kind of expecting a stage from there, given how other DS games were getting stages too.
Complaining on a Internet forum won't solve anything, but one can't help but think about why things are the way they are.