The bag and bank and reagent storage system needs simplification.
Infinite 
Void storage or other that u can throw anything that is or can be used towards any profession ingredient.
It would be nice to be able to do this account wide for all toons….
I spend so much time throwing stuff away or trying to figure out what goes where for what expansion or selling stuff.
Maybe a bag that is only for quest items?
I call it the Full Bag Boss eats up so much time.
I don’t know 
I have been playing wow since Vanilla till mid way through Mists, took a 7 year break and I get back, it’s quite overwhelming, don’t even get me started on the profession interface . I don’t want to even try to hard with it. Just one Point of view 
There is the warband’s bank. What else do you need. Void storage is a much more long term, close to useless, kind of storage. For mementos and sometimes items that are no longer available.
Unless you are a hoarder, you should have plenty with the warband’s bank. Only thing I do not keep or remove from there is LW and tailoring stuff. Only got 1 of each those and their mats are very much aimed them.
As a compulsive hoarder of game items myself I can totally understand!
I have an addon called BagSync which tells me what an item is, what expansion it’s from, and which of my alts has that, where they have it, and how much they have.
For example, it tells me that Artisan’s Acuity is a trade skill item, other category, from The War Within. It tells me how many I have on each alt, and where it’s at (all in my bags cause they’re soul bound). It also tells me that I have the depressingly hoarded amount of 17,681 of it across 16 alts.