True, but you want a dump that is relevant throughout the expansion. If you only come up with limited use examples, then the dump has limited use. Here's why your examples are of limited use:
Transfer OHR: That's not a dump, that's basically account shared currency (which I would very much like with other currencies).
Follower equipment: Only useful for as long as you need to fill out your champions. Only continued use would be to swap out on a per-mission basis, which is not what Blizzard wants with this system, so not going to happen.
Buffs: Once you reach a certain powerlevel, you stop caring about buffs and just run in head first. Lowgeared tanks can already charge in to masspull and survive, so in all honesty, what type of useful buff would they want to buy? My priest can spam SWP and Mindflay and survive most stuff already.
One-time cosmetic rewards & Transmog: Even for large amounts, it's still a one-time purchase. Then you have no more reason to dump resources.
This kind if dump is only relevant for a short while. If they implemented it today, you would most likely be DONE before 7.3 hits. Then you have the rest of the expansion to gather resources and spend them on absolutely nothing. Just like now.