I owned a Push 2 for 2 years before I sold it, and in my experience there is very little (if anything) it does that cannot be done with a 1:1 analogue in the software.
If you are at all code-savvy it is very easy to make your own custom rig that does everything everything you need for live performing in Ableton. You can write your own control surface scripts in Python (unofficially, but google is your friend and Ableton said "we know they're out there and we aren't going to try to shut it down") and you can make anything you want be your own customized equivalent of push with Max for Live. You can do anything you want with your clips and loops from either control surface scripts or M4L devices. Ableton itself was originally just a Max patch!
Sure they've made it easier, but it's definitely not true that you can't do this without Push.
What did they do to cripple the features of non-push interfaces? As far as I know the monomes, apc40s, etc of the world continue to work as they always did?
Pad controllers are dime a dozen. I've never gotten the impression that Ableton was willfully sabotaging the market there.