Well, environments in DKCR are certainly more detailed, expansive and there's more going on, both scripted and real time... With that said, I think they should have lifted the DK polygon model from Jungle Beat along with the fur shading technique, should be certainly doable to do, even if it's use was limited to cutscenes and close-ups.
Jungle Beat... well it certainly has some bad textures in there, that I never noticed before. I assume they were actually placeholders that were left in the game considering (and pointing out) that sometimes you have a good/better leaves texture next to pretty horrible one's.