Well, they did reuse the hell out of Ridley in the Prime series, and I don't think Mother Brain was ever really established as a primary antagonist. She's only prominent in Metroid and Super Metroid.As someone who honestly is a bit of a Rare hater (Donkey Kong 64 ruined my childhood), I think K Rool would look fine with a tail.
Like seriously, give him a fucking tail.
Dixie should get in before any other Donkey Kong character though.
Again, Retro likes making new stuff for a franchise and that's why they haven't reused the Kremlings. They didn't reuse Mother Brain either, but that doesn't mean there was some vendetta against Mother Brain. Nintendo has no issue with including Kremlings in Smash Bros, so why would they have an issue including them in Donkey Kong?
As a further response, I'll present this quote from another user:
if nintendo just hated k.rool and kremlings and rare and just wanted to do away with them, why would they replace the tiki tak tribe in tropical freeze? they had already served their purpose of replacing kremlings.
it seems pretty obvious to me that nintendo (or retro, can't say whose decision it was) just doesn't want a primary antagonist for the dk series anymore, and would rather it take the villain-of-the-week approach, with each game having a new enemy.
As a quick response to this particular quote, I'd say that very approach is actually supportive of my opinion that they have more or less abandoned Kremlings as anything more than a relic of the DK series past, and bring up that Nintendo themselves have had ample opportunity to continue featuring Kremlings in Mario spinoff titles that have released since Sluggers in 2008, including the Mario & Sonic Olympic games series, the Mario vs Donkey Kong series, Mario Sports Mix, Mario Kart 7 & 8, Fortune Street, Mario Party 9, 10 and Island Tour, Mario Tennis Open, and Mario Golf: World Tour--and yet, not a single Kremling, despite their pre-2008 comeup appearances in Sluggers, Strikers Charged, Strikers, and Power Tennis.