Stuff like ships and shaders don't get "old" and I like to keep at least one copy of each, but since we can't sell mats anymore I've got no space for those either.

You're pretty clueless it seems. Deej has already responded directly to one of these posts nearly a month ago and verified that they are working on the best way to implement adding space into the game. So it's not a question as to 'if' its going to happen, but rather, 'when'. Though I'll agree most of the crap people want to keep is in fact useless, but hoarders gonna be hoarders...