There's no reason why proficiency should increase throw range or shield bash skills, except for the fact that wielding a shield requires proficiency in shields. If proficiency did improve these things, then it would also have to benefit all the other weapons for consistency/balance.
Height is a perfect thing to increase throw range. Or you could wield a javelin, which is more suitable for throwing and thus has a larger range, at the expense of no ability to be wielded with two hands.
