An admin option to allow "uploaded files included in gallery" would solve that wouldn't it?
Most people want something quick and easy. So being able to upload xenmedia images straight from a "create thread" would make things easier and faster.
We have lots of users uploading images to posts but hardly anyone using the gallery itself. The gallery provides a very nice way to view, comment and rate uploaded images but it's currently not integrated with the majority of the image-based content our users are generating.
I'm not saying that I don't like the idea of being able to do what has been suggested, it's just that some thought is needed to get it to work well and with various permutations of how people use XFMG.