Does a crash make you a better driver?
Only if you survive.
I can only begin to asume that inexperience when driving a RWD has a lot to do with the majority of comments in this thread re, (Back end stepping out).
Iv'e found that unless there is outside influences which cannot be foreseen it's almost impossible to get the back end slipping without being over zelous with the right foot.
The Z is such a great car to drive it's all too easy to get carried away and fall to temptation to push the boundries. Im my experience drivers skill levels, fall far short of the levels of grip of modern day cars so when grip does give way it's generally at too higher speed thus normally no way back and the enevitable happend.
Having said all of this, and to answer the original question. There is no substitute for expeirience so if you can walk away from any crash providing you learn from it then, yes crashing should make you a safer but not a better driver.