Just because an older character is remembered and requested on the internet doesn't mean they were a huge deal. Look at Isaac. Or Takamaru. Kid Icarus was known, sure, but comparing its reception to Zelda or Metroid is pretty dubious.
Considering all that would happen is typical Smash tantrums, I think they'll land on their feet either way.
But Kid Icarus actually was placed on the pedestal right next to Metroid and Zelda back in its day, Nintendo promoted it as a major title of the same caliber as those other big names. Kid Icarus absolutely was regarded as one of Nintendo's greats back in the late 80s, heck, they even put Kid Icarus as a major character in Captain N the game master, above Samus and Link even... Nah, everyone who thinks Pit was just another rando and bias pick is clearly either misremembering, or doesn't have their history straight. It was even destined for multi generational releases, sadly that didn't turn out due to unforeseen circumstances, but it was destined early on, and that's why Sakurai decided to update Pit's design in Brawl as if he had continually gotten generational game releases, just as Link and Samus had gotten, because that's what Kid Icarus was meant to be... Unlike Balloon Fight, Ice Climber, Urban Champion, Clu Clu Land, etc etc.
Takamaru was much earlier, never released outside of Japan, and was not made as big of a deal when it released, but still bigger than most of those other minor games, could be why we have an Assist Trophy of him but not much more. And Golden Sun, as previously stated, was an out of house development project, and those have a big uphill battle to deal with, as Nintendo doesn't often push for them as much as their in-house games (like you rarely see cameos and references to those games in their EPD and other partnered game releases, but you'll see in-house IP referenced and cameo'd all the time, just look at WarioWare, Animal Crossing, Mario Kart, etc). Kid Icarus though, it got references... Remember the Tetris end screen? Heh.
Sorry I keep getting this place off topic... I really do want to keep the focus on Banjo-Kazooie, and I suppose I could haphazardly tie them into the conversation, umm, by uh, heh, by saying Banjo-Kazooie was basically the Kid Icarus of its day! It was huge, it was promoted heavily by Nintendo, destined for greatness, and then all of a sudden only a generation later, it was gone!! HAH! I did it!
