Cures are obtained from spells and abilities. Remember, this is a land of magic. There are herbalists and holy people with magical healing powers.
You have not acknowledged that Medicine is not used with healing kits. Regardless, Healing Kits are also useless (w/the exception of the Healer feat) because Healing Potions are so much better.
I use medicine as well. I agree that the curative qualities can easily be overshadowed by spells. Medicine does not require the taking of the spell or spending a slot, however.
Where medicine shines is in a murder mystery campaign. It gives players the ability to be the medical examiner to determine things like cause of death, time of death, murder weapon etc by examining the remains.
TV is full of crime shows that can provide inspiration on medicine as an information gathering tool. It falls to the player to attempt the actions along those lines followed by the DM giving a DC if needed. The only thing stopping such checks from entering play is in not attempting them or mispplying which check to make.