With you guys pretty much changing how zones work there is no need to allow chests to drop at different levels in your range, so make the chests stackable. I see so many complaints about this, it could be because it is the anniversary it has become more of an issue, but even without the anniversary lots of us were asking for this to happen.
I can guarantee you having chests not stackable does not make people want to buy stash. They will still buy stash because usually what is IN the chest is what they want to keep. Chests are usually opened once the inventory is filled, not filling stash tabs with chests that you're going to open later.