I would love if I could filter out items I already own.
I have a sizable collection of content I've purchased from the content store, which means it's hard to discover new things. I regularly come across a product that looks interesting only to find out when I go to the checkout that I've already purchased it.

yeah, seriously...

Maybe there's an option there somewhere and I'm just not seeing it, but how is this NOT a thing that's already happening by default?!

So frustrating...