I think the jail clauses are in there to act as a chilling effect and deter employers from putting in the clauses at all without consulting an attorney. Basically playing the Uno reverse card on employers who put unenforceable non-competes in contracts to deter employers from leaving.

In principle, I agree that jail time is too harsh, but I have to admit I find it satisfying to turn the tables like that. Plus it's not like the jail term is ever going to be used.