Arms

Can someone explain to me why action figure toys of now-a-days arms are detachable? I don't remember this as a kid. I played with my fair share of ninja turtles, hulk hogans, and he-mans. That was the good part of action figures compared to barbies. No matter what, your barbies head would come off and never go back on that white ball thing. I have 3 Jack Sparrows at the moment all missing something.