I never have anymore space

[Pandastirfry]

Sure, if you're willing to spend twice as much time on inventory management as you spend actually playing the game, you could check all that and pare down your inventory to just the most useful items. But for people who don't want to devote the majority of their game to inventory, it has to be a much shorter set of questions, something like:
Is it a crafting ingredient? Yes. Do you do any crafting? Yes. --> Keep.
And that makes you run out of space fast.

you actually had the most important question in your first paragraph... really the only question worth answering " Am I going to want any of those items any time soon?" but just change "want" to "need". if the answer is NO get rid of it, nothing besides the starred gathering mats and philo mats could be considered "rare" and a must hold onto mat...everything else can be farmed up quickly and easily on a at need basis.

seriously if your Inventory looks like a Very Special Episode of "Hoarders" MMO Edition, it's your own dang fault for not just keeping the things you need, but holding on to all those bits and bobs, odds and ends because you might use them one day...maybe...