I couldn't agree more with this kind of change. Buying Cordials/Ventures/Coke is definitely a clunky mess (Took me 5 minutes to buy 163 coke .-.). I feel as though a complete overhaul of how the NPC merchants work would be in order, as we can't do, for example, shift-click to bring up "How many would you like of X?" Then you select from 1-99. This method can also help make working with different merchants more consistent (This kind of thing wouldn't apply to non-stackable or unique items, for very self-explainable reasons). I can't say how PS3/4 does their interactions with merchants, so that's beyond me right now.