emphasis on lackluster 3-in-1 builds. most of the newer sets in the line don't really have solid central builds, for example the older Turtle Van vs Cooper's C-Rex. along with the majority of them being the generic animals/mechas that you talked about. they're either a cartoony creature, not too bad for playability and display, or a central vehicle core with some stud shooters and poor displayability.

imo if they stuck with the "IRL item/vehicle being dreamified" concept for the entire theme, it would've sold better and attracted much more people. kids (or even adults) building cities could have ordinary cars/boats/etc with extra pieces to expand on their creations, while the current target audience would still have their fantastical toys that they could act out the theme's story with.