To me, the point of the crush system in Tekken is to prevent people from just backdash cancelling forever and doing a d+1 to keep out forever and such. The characters should have a move that can bypass those quick lows as a means to deal some damage and begin offense. It shouldn't become their go-to move to deal damage. Things like Matterhorns, lightning screw, and AOP u/f+3,1 are all crush moves but really become ridiculous with how much reward they get. I came with the notion of crush moves not launching based on the way Tekken Revolution handled invincibles where under no circumstance can they ever launch.
EDIT: Looking at those examples I posted, my problem is more with mid-crush moves rather than simply low crush LOL.
For the most part, I agree with you. Especially about the mid ducking moves (no surprise there ). Like I said in my last post, the reward for crush moves hitting you normally is way too high. The thing is, you can't just make a sweeping change like that without heavily retooling the characters. That is why my suggestion is based around still granting extra damage after a hopkick connects normally, but just making it a much shorter or weaker combo (like Jin's hopkick on regular hit).
It also seems silly to actually be punished when you're actually trying to utilize the crush system. As long as the crush system exists as it is, I can't agree with you on that one.
As far as mid ducking launchers go, outside of stances where the character's can't block (AOP), that bullshit has to fucking go. I don't think I have it in me to handle another Tekken game that's full of that nonsense.
EDIT: Removed a portion that I typed up during an apparent brain fart.