Why dont people use Higher equips?

Because defense is useless. If defense had any use, people would be using higher level equips as they give more defense. Its only helpful in the very early lvls. But since it isn't, people choose low level equips since they have a lower secondary stat requirement, which leads to more points put into their primary stats and a higher damage.

L> defense Revamp

but what about the 4 free str?

lol but seriously.. its cuz if you scroll a bathrobe, every class can use it, but a pirate overall is in much less demand.