On the CGI aspect it really is sad how much better even Frozen looks in hand drawn animation.
I think it really just depends on how they use the medium, and if they are using it to its full advantages.
For example, Tangled and Frozen could both easily be hand drawn, and they'd probably be better that way, because story-wise they don't rely too much on the CGI advantages.
On the other hand, Wreck-It-Ralph, the Despicable Me movies, and the How To Train Your Dragon movies use many aspects of CGI that are unique to that type of animation in ways that really involve the characters and drive the plot. I couldn't imagine them being as good if they were 2D-style.
There might even be stuff that is 2D that would benefit from the 3D more so and would help the story. For example, as cool as 2D SW Rebels may be, I just think the 3D would work better because you aren't so limited. Just compare the action between Clone Wars and The Clone Wars. No matter your opinion on the overall shows, I find it hard to argue that the first 2D series has more engaging action sequences than the 3D series. It simply makes sense.
See, what I think the problem really is the idea that people in the movie business have gotten a tad too attached to the newer 3D CGI technology.