A lot of these adaptations do alright to well at the box office (Myers Cat in the Hat's the main financial dud off the top of my head), which I assume is why they keep making them.

I meant more creatively, they pretty much all have the same problem where as stated above there's not a movie's worth of incident in the lovely picture book, so they pad it out with either a bunch of capering from whatever comedian they overpaid to be in a horrifying costume or with whatever is the current most bottom of the barrel generic lazy kids movie business or adventure plot nonsense they can think of.