That's funny, because
@A F0xy Grampa gets out of the corner all the time, or at least forces me to check myself before running in a 50/50 or grab, and he certainly punishes the B2 100% of the time it's blocked, and will MB spin the Ice Ball from B33.
Any character with an armoured move will reduce any advance from a Klone in the corner to a minimum, and it will stifle the corner game massively...try flow charting corner Klone stuff against Thunder God Raiden with a bar and eat 38% while being pushed almost the other side of the screen, or Reptile, and be lunched into a slow force ball mind fuck, or even against Sub Zero himself and have the tables turned instantly with a MB slide...
There are other punishable things to consider, If I put up a Klone from 123 Slide in the corner, characters can MB wake up through the Klone, and they can also armour through anything I try to do If I get greedy once the Klone is out.
Im not saying it isn't good, and I'm not saying some characters don't have better options that others to escape or punish in the corner, but in time, you will see.