The problem with RNG is that it is simply RNG. It is only based on luck.
The only possible thing I see they can do with the current system (that wouldnt negativly affect their platinum scheme, actually it would benefit from it) is to create a meaningfull crafting system, where you could be able to craft a lot of different and useful items with your crafting materials. That way you can actually transform all those crappy items you are bound to get into something that you in the end actually can use.
They could also expand on the current chests, giving people more expensive chests with better, or more items, costing more gold. Or even specialiced one off chests, that give better items. Like a reward of some kind. I would prefer them giving different types of chests from accomplishing some of the 5 points-achievements.
Another thing they could have done is that they could create a system where players could actually increase their chances of better drops outside of the store - a small number that increase with prestige, promotions, or actual player skill. Lets say you could increase your one time chest opening by completing a perilous mission or something similar. Thats not going to happen though as they cant vary peoples chances on something that they want people to buy for money - as that wouldnt be fair to their customers. It's a shame though, because I think a lot of players who dont like the current system wouldnt feel so ripped off by it if they could affect it in some way, and also see the results from it.
I would personally prefer an in-game drop system - where you gather all of your loot from in game mobs or chests or both, instead of outside the gaming - in a microtransactions shop. Something similar of the current diablo 3 system, without the marketplace they had in the release version - which totally ruined the game.
I personally have no love for microtransactions in games. Not at all.