I'm skinny and I like to be fucked like there's no tomorrow. I like having my nipples twisted until they are purple, I like to get strangled, slapped in the face, and fucked so hard that it hurts the guy. Just because fat chicks have cushion for the pushin' doesn't mean they are the only ones who can take a good pushin'.
Look at it from a male's perspective:
I've been with women who loved to be bit, suckled, and scratched, but who would have freaked out if you slapped them.
I've also been with with women who loved to be strangled or cracked, hard, right across the face when they came, but who were otherwise so physically sensitive that they could not stand to have teeth so much as graze their nipples.
Unless you actually communicate in some way just where your boundaries are we are stuck flying blind, and trial-and-error gone wrong is a fucking hassle.