Stop the **** about relevancy not mattering for newcomers, it's plain as day that it does for everyone that isn't a retro pick.
And the Smash community's favorites show age. K. Rool, Geno, Banjo, but also stuff like krystal and Isaac makes it super obvious are the "core" fans are from the 64-GC era or older. And "but Warioland" is also part of the pattern here.
There are reasons this fanbase mostly want to fill out older series with characters.
And Ridley unlike those above mentioned character is actually still relevant.
and if we want to use not coming in until the finale as an excuse, why is Bowser and why was Bowser considered the most iconic villain in gaming when most of his portrayals have him show up as the final boss only in the main games and people constantly butcher his name as "Browser"?
In the original SMB he's literally every boss. In 64 he's three times + the game over thing. there's also literally all the mario spinoffs. He's iconic partly because of his constant use in mario games and media.
Only DK+Smash fans that know who K. Rool is.
Smash has a unique position where it can revive dead franchises and characters. it did this specifically with Kid Icarus after pit was added to smash, other games like earthbound got a huge boost in popularity retroactively after Ness was chosen as one of our first smash characters. Even things like Game and Watch and R.O.B. get waaaay more attention than they ever did before smash, i barely was aware of either of them before hand.
So thats one reason I think characters like K Rool, Geno, and Banjo Kazooie are so heavily requested for the game. These are characters that got a huge fanbase and were once beloved nintendo characters but for various reasons fell into obscurity despite people really wanting them to show up again.
when geno had a minor cameo in the mario and luigi rpg games, i was thrilled he wasnt forgotten. people desperately wanted K Rool to show up somewhere in returns or tropical freeze. Banjo-Kazooie feel like they are essentially being held prisoner at this point.
So not only do these characters have large fanbases, their fans have also not forgotten them despite all the odds and really feel smash is the safe haven to rescue them and keep their legacy alive and relevant for years to come.
I Genuinly don't Kid Icarus would have gotten a revival hadn't Sakurai done it himself. Earthbound, Fire Emblem and some old stuff might have gotten more attention. But Where is the Ice Climbers revival? Duck Hunt? more little mac? Smash might be able to revive characters but it hasn't really shown that it revives franchises.
It's not lack of Smash appearance that stops Rool from being in DK games, it's because the developer don't want to use him.