It is after all a co-op game and so far all we can flaunt during missions are our creativity with colors. I think they should have just made some kind of exclusive buy-only skins, particle effects, sound effects, or other cosmetics that look good enough to show off with. I would rather buy stuff I can use in-game and not stuff that is just for hoarding. No matter what I would have to decide a cutoff limit to avoid having more than I would actually use, but who knows how weapons and frames will be adjusted over the life of the game. In the long run I don't think I should be chasing that kind of carrot.
Is there an upper limit to inv? If it's infinite then to collect all weapons and frames I'd be buying inv for the duration of the game's life. There's two things I'm always thinking of when looking at inv slots:
I'm more or less just trying to manage it as best I can without paying for extra space. They've actually made me not want to get more items because of this.
I have to agree with the inventory thing.