Lack of potion/Ether use

[Matsume]

If it is not necessary to the success of a mission, most players will often forgoe costly luxuries such as these. There is no argument against the usefulness that they represent. Certainly a number of deaths and perhaps wipes could be avoided. But as the above post mentions, most players up until now have done very well without the use of such alchemical products. It will take time as much as difficult content in order to change this habit.

[Urthdigger]

most players will often forgoe costly luxuries such as these

This. If you want players to use them, you need to make them cheap. Even food isn't that expensive, and it lasts for half an hour. Medicines are either an instant effect, or last for a mere 40 seconds. This means that if a player is going to be using them effectively during a fight, they will be using several.

Whether it means popping potions to help survive a heavy duty boss or to reduce the need for the healer to heal folks other than the tank, or popping ethers to allow you to blow your MP away like crazy, or even using the various stat potions, any strategy where medicines are used will usually require a lot of them to be used. People will not require this a viable strategy if it requires plopping down an extra 50k each fight. However, if it only requires maybe an extra 2k gil spent on medicines, folks will be a lot more willing to spend the gil. I know folks can get plenty of gil from leves, but folks tend to be stingy when it comes to consumables. It's easy to justify spending all that money on a highly expensive piece of gear: It may last you for the rest of the game, and you can sell it back if need be. Spending a lot of money on potions is a different matter: It lasts you those 40 seconds, and then that money is gone, never to be seen again.

If you want players to not see them as a luxury item, you need to start by not seeing it as a luxury item yourself. I use plenty of potions myself, but that's because I make them myself for cheap. Hell, throat drops saved my party's ass last night. If I had to spend 50k gil over the course of a fight to avoid silence though? I'd tell my tank "Sorry bro, I was silenced. Better luck next time."