It's not that people wanted K. Rool to Hijack Fredrik, but Fredrik wasn't different enough to warrant a new villain.
KAPTAIN K. Rool had more differences from
KING K. Rool in his final boss fight than Fredrik did with the King. His silhouette being almost identical to K. Rool's didn't help one bit either. Bashmaster would have been a better final boss in my opinion as he was different both visually and actually had an original fight.
Tiki Tong however, could have used a good old fashion Ganon styled hijacking.
The reason why people like the Mario RPG villains is because of their range of personalities, something that all these villains in the DKC revivals do not have... well Fredrik has traces of personality...but that personality is still just K. Rool's (big bad villain who is menacing from afar, but when confronted is kind of a goofball). People don't talk about Grodus from the
good Paper Mario sequel because he's pretty dull. Same with the boring Shroobs of Partners in Time, they talk about characters who had an interesting personality like Fawful (I personally find him over rated, but can say he has stood out in comparison to someone like Smithy).
When it comes to different villains appearing all the time, look at the Wario Land series, aside from the first two games it has had a different villain every game...but the only villain worth anything is Captain Syrup. She didn't have much of a personality at first and her main attribute was that she was a female villain. (we also got Golden Diva and Terrormisu later...Wario does like beating on the ladies...) Her latest appearance gave her a personality and even made her relationship with Wario different from Mario and Bowser's, or even Donkey and K. Rool's. Wario and Syrup's relationship is somewhat like a Batman/Catwoman-esque one...only both are greedy self serving jerks. Captain Syrup is Wario's Peach and Bowser combined into one package... She was in a similar position to K. Rool when it came to being the only villain worth mentioning in their series.
Ahem...sorry got off topic... having a revolving door of villains doesn't really do much when these new villains don't appear more than once or have any dialogue. Look at Kirby's series, that series has a different villain every game. In fact the only recurring evil the series has had was Dark Matter, and by extension 0. People stop caring about characters like Dark Mind or Necrodeus when the new flavor of the month shows up...in fact I'd almost say Whispy Woods is more memorable since he shows up so much... I will say that other one shots like Marx or Magolor are loved because they actually talked and had a semblance of a personality. That and the Kirby series loves to self reference itself all the time, so characters aren't completely thrown away.
As mentioned before the Kremlings and their leader changed appearance every game. So the "Bowser" argument doesn't work. Especially since a majority of the time you are STILL fighting the same enemies anyway in the Mario games without Bowser as the main villain. To tell you the truth, if anything the Kremlings could actually USE some uniformity. Rather than creating a whole new design for the base Kremling, they could take a page from their leader's book and simply have different duds to fit whatever K. Rool decides to dress up as. So a Kritter remains a Kritter whether wearing his tattered pants or Pteryges (the skirt of the Greek armor). So like K. Rool the design of the enemy remains the same, but their clothing and weapon changes. Like Klump to Kannon.
Why did they not name Bazuka Karbine and just switch the name with the owl enemy ala Ostro and Birdo.
As for my unpopular opinions...
Retro's artstyle is UGLY... most of their bulging eye enemies make the enemies in DKC3 look cute...
I actually like K. Rool's PAON voice and design