I started to write a reply, but the more I thought about it, the less it seemed to matter.
In my opinion, the waist is a more intimate body area than the hips, so in non-safe images especially, it has a different mood to me. Of course, that's subjective.
It also makes a difference whether it's one's own hand(s) or someone else's, but that's not accounted for in the tags and would be getting convoluted. (There are plenty of other tags related to touching that similarly make no distinction.)
Then there are cases when it's factually correct (eg. NSFW >>2658046
) but not the "hand(s) on hip(s)" pose, which makes it even less focused.