> To be fair museums themselves make this worse. I still haven't come across a museum (granted I don't go a lot) that had exhaustive good-quality photographs of all their exhibits available online.

Bingo. I do go to a lot of art galleries and museums and this is a huge problem. I get back and want to find that item that was very interesting and study it more, and the best I can find is some grainy picture on wikipedia that someone else took.