Maybe there could be a regular fee to pay (daily/weekly/monthly, with cash or CE) to keep weapon and trinket slots open instead of going to boost every month to buy the silly upgrade items?
Well, there is still the problem of dealing with inactive periods, but this board is for discussing and improving these suggestions, isn't it?
Um. There already IS a monthly fee in CE to keep weapon and trinket slots open.
So...you're suggesting that things should work exactly like they already do, except that you should be able to buy upgrades without talking to the upgrade merchant?