I can understand your concern about medicines not being too useful. To be honest, OP, I didn't realize what their point was either... But then when I started doing the first Coil, and now especially the second Coil... their uses are becoming more and more clear. Sometimes, using mainstat pops, mp pots (so bards can squeeze out more dps by not ballading), and potent poison pots can mean the difference between hitting a hard enrage (death) and beating a fight before you are insta-killed. As an example, we brought a bard into T8 the other night who didn't really have any gear from coil. He was a friend and took our static bard's place for the week. We had a lot of trouble beating T8 because of lack of damage -- partly because of his lack of gear. We were able to clear it with ease before bringing him in, but to make up for that lack of dps, we all started using pots (more people than before). I can pop two or possibly even three int pots in that fight if I time it right. With potent poisoning potions being on a less than 2 minute cooldown (hq), you can pop at least five. I pop pots on every fights, but not every person was because it wasn't needed -- but then we were at the fine line of needing it. Before people received more and more gear from earlier second coils, these medicines were needed to beat the tight dps checks of the later turns.

These medicines really don't get much use outside of situations where you REALLY need to push everything you have, although I have noticed myself using MP pots (for healer) in situations where I am starved for MP. For example, I might be doing Titan extreme and wasting a lot of MP on raises... but our bard is dead so I don't get ballad. So, I can pop a mana pot in addition to shroud or energy drain.

Considering the balance needed regarding the tight dps checks on the harder fights, I don't think they should change the pot cooldown.