Before hormones I got that too. After epilating my legs, my upper legs would end up with permanent small red bumps and some of them would become almost acne-like as the hair came back, even if I exfoliated daily. After I started hormones, that stopped. I think the change in skin from hormones has an effect. Also much of the body hair (even on legs) has either stopped coming back altogether, or is much finer and lighter in color.
I don't really know if there is a way to stop it from happening, I may not have been exfoliating with the right scrub or sponge or whatever and like you said may have needed something more aggressive for my "male" skin.
I haven't bothered with my arms because with hormones that hair is likely to diminish a lot on it's own, and it was never all that thick in the first place.
I love my epilator, and will likely never go back to shaving my legs.