Right now if you buy additional stash or inventory tabs, its only good on the one character you buy it for.
That's not really a good model (at least not at the price point) because you can always just buy a character slot and make a new mule. Its a little more inconvenient, yes, but that's several times more storage space since every character starts with several tabs (and can unlock a couple more in-game fairly easily). I'd like to see stash and inventory tabs become account-wide (even if it means increasing the price a little to compensate), so that you unlock a new slot on every character when you buy one.
Does that mean way cheaper storage for players? Of course. This is one of the top longrunning complaints from the playerbase. But this isnt just a "gief free plx" thread, I think it would be a sound business decision for SSG too, because instead of tabs and char slots competing with each other, they'd complement each other. The more character slots you buy, the more storage you get from each tab you buy. The more tabs you buy, the more space each new character slot you buy gets. It'd encourage you to buy both. Its like power creep for SSG's revenue stream.