Like level one of a libreoffice effort would be to organize all the buttons on all the dialogs and make sure they are consistent, or something like that. There are probably a couple hundred standard ones, it's not sexy. It is some work though.
A level 10 would be doing something like reinventing the ribbon from office, which might be more of a gtk+ task than a libreoffice task, and the libreoffice guys might not even think that's in their domain or their problem. I think that could be a justifiable position too.
You have to actually collaborate a lot with the team just to find all of the work for both of these. Ux guys don't seem to be dedicated enough to those projects. And fwiw, the projects themselves might not be open to spending energy "reskinning" especially when libreoffice has so much other technical debt.