If efficiency was the only thing everyone cared about we'd all be using vit gouged chaos rapier hornet ring builds. It isnt everything
48 strength allows you to use the forest guardian axe, which is one of the funnest weapons in the game, 50 allows you to use the dragon king greataxe and dragon greatsword; BOTH of which are badass by the way, and kick Ass too.

And the black knight weapons are obscenely fun to use, and every strength build i have has a minimum of 18 dex for them.
Strength builds are mainly because they're AWESOMELY BADASS, why limit their badassery and fun factor?

And ultima was kidding about the resistance deprived.