I'm on-board with medicine adjustments!
Here are a few ideas that would be lovely.
I apologize if they've already been stated:

1. Medicine (Potions, Ethers) stack to 12 (or 99!)
2. Remove medicated effect on Potions, Ethers.
3. Increase amount of HP and MP healed with items.

Potions are wonderful items. I spend a lot of gil on HP and MP restoring items, but I am limited to only a few items out of the plethora of medications out there simply due to the amount of time it takes to use an item as well as the medicated effect that they cause. This limits me mainly to Vile Elixir, Vile Elixir +1, Hi-Potion +3, and Super Ether +3. These are not always in stock and limited. Additionally, they take up a lot of space because I use a lot of medication.

This is a bit far-fetched, but I thought of a creative solution to potions and ethers (excluding elixirs):

Potions
HP Healed = (Max HP / X)*(1+Y)
X = Modifier based on the level of the potion (i.e. Hi-Potion vs Super Potion).
Y = MND based modifier, much like a WSC in WS formulas, also affected by level of the potion.
Potions would be affected by MND and your Max HP, making healing much more efficient.
Additionally, make (certain) potions target party members, and make area of effect potions craftable.

Ethers
MP Healed = (Max MP / X)*(1+Y)
X = Modifier based on the level of the potion (i.e. Hi-Ether vs Super Ether).
Y = INT based modifier, much like a WSC in WS formulas, also affected by level of the potion.
Potions would be affected by INT and your Max MP, making healing much more efficient.
Additionally, make (certain) potions target party members, and make area of effect potions craftable.

Final Adjustment:
Much like Automaton Oils, add minimum level requirements to use them, like the requirements of EXP pages.
This way you don't have low level parties spamming high healing items.

Anyway, that's just my two cents. Hopefully my ideas get those brain cogs turning!