Lore-wise, the form is intended to be stronger. It wouldn't make sense to fight in human form where you're weaker and more vulnerable.
Some take pride in who they are now, and have adapted to life in their Worgen forms and some even prefer it that way.
- - - Updated - - -
Are you saying they don't have enough control to move their bodies how they wish? It's not like they're not in control of their limbs - everyone can punch and kick.