You know, maybe DK didn't get a new character in Smash 4 due to the fact that Sakurai is biased against the franchise.
I mean, look at the stages. Every one of them is a jungle.
Look at the music selection. The majority of them are variations of the same song.
Look at the characters. The fact that DK has less characters than Kid Icarus shows that a new DK character wasn't a high priority for them, despite the massive success that was Returns.
If Sakurai weren't biased, we would've had Dixie and K. Rool in Smash by now.
I don't see the problem with having a jungle stage, that's just them not having the time to make a stage. Would I like to see a new stage from DK? Sure, i'm just not sure what it would be (I've heard of the Mine cart stage, and while it does sound promising, I don't see how it could work). There's also 75M, where as much as you may not like it, is still a stage.
Music selection, I'll give you that. Seeing more songs would be nice (As much as I love the current remixes).
Kid Icarus would have the same amount of characters as DK if it didn't have Dark Pit as a clone. It was never meant to overtake DK in the amount of characters it has.
On top of that, DK and Diddy are VERY faithful to how they are in their own games. Their animations, the moves that they have, they come straight out of a DKC game (DK possibly even inspiring some moves for future DK games). To say he doesn't care for the series is a lie and wrong. If he didn't like it, it would only have DK, very few trophies, and a stage at best. Just because it didn't get a character, doesn't mean he dislikes the franchise (If that's so, might as well include F-Zero in that).
Honestly, the only thing I felt like that could've held King K Rool back is his weird hiatus state. He's still popular, and a big figure in DKC. However, because we're not entirely sure of his status right now, he was probably put on low priority. That's the only thing I could guess.