I think potions are a) too easily obtained and hoarded b) can too often be used en masse to muscle through tough fights and c) because of a, b and they are one-time-use only, saving and loading tactics are indirectly supported against using consumables.
Would it be possible to make potions both stackable consumables AND have a limited use per day? This would involve finding that magic number of how many times per day can potions be used to keep key battles well balanced while eliminating the support for hoarding huge amounts of potions so you can use 20 of them on one character for that next huge fight. In-game reasoning: too many potions will actually poison you.
Or, make healing potions refillable, aka: charged. This would involve implementing variable recharge prices for varying potency of healing potions, but doing so could make it possible to refill other consumables like potions of heroism and haste and the like. Make some of those REALLY expensive (gold sink anyone? Maybe this should be called "RICH Man's Cooldown).
Or or, imbibing too many potions will still heal you, but with diminishing returns within the same fight, or conversely, will poison the imbiber somehow -- something similar to haste potions' fatigue effect.
There are other things to consider to make this work, like re-distributing the amount of potions and their prices throughout the game, but I think this will keep potions just as if not more valuable per fight, but less valuable to hoard. I think this was a somewhat common gripe for this and many other games that use hoard-able healing potions and maybe this is the wrong solution for it. Open discussion for other suggestions.