True, and worth reminding ourselves of. When something is as mind-blowingly enjoyable as sexual dominance, it can be dangerously easy to get swept away and forget the responsibilities that come with it.
This is one of the places where succesful BDSM requires a certain amount of doublethink. On one level, it can be part of the fun for both of you to treat the sub as a thing to be used for your pleasure without a thought for hir feelings. But there must always be another part of your mind that keeps aware that this is a person with feelings that matter, and watches out for them.