I think the stacking bug is caused by items that have different graphics despite being otherwise identical. I know candles will only stack with other candles that look exactly the same, and since there's a lot of different candle appearances, you can end up with a lot of stacks of candles in your bag (assuming you're actually taking candles; there's a lot of them, nobody cares if you take them, and they sell for 1 gold each, which adds up). It's probably the same issue with other items, although I really don't need equivalent health potions to have different graphics. If not graphics, there's just one thing different that makes them not stack.
Personally, aside from the candles (it'd be weird if they all looked the same), I could do without the slight variances in appearance of stackable items. It's not like I'm ever zoomed in far enough to see them, anyway.
