Making crush through blockable only on active blocks would add more complexity to the game, which is doesnt need. At this point theres a billion things to keep in mind when fighting in melee, adding more to that will just make the skill gap between players even bigger, which as far as Im aware, is something Taleworld doesnt want right? People arnt mastering the combat system because its hard, but because its not fun.
Once again its a system that was pretty much perfected in Warband, that wasnt taken into consideration when adapting it to Bannerlord. Add it on slow weapons with massive weight at the end, so mauls and hammers and thats it.