You're facing off against a boss. Your party is looking ragged; one member is down and another is barely hanging on, but you're afraid that if you heal them and they drop anyway, you'll be even worse off. The boss is in fine form, but you're sure that you can best it if you can just hold the party together a little longer. You have a few ideas in mind, but...

Then you just have everyone pop a consumable and all is well.

Poof. Tension gone.

The cardinal Rule of Healing is that tension is inversely proportional to the ability of the heal to mitigate enemy damage. But, for some reason, there are games where healing is plentiful to the point that it totally curb stomps threat. Of course, this is rarely on the Dedicated Healer, but often in the Healing Consumable Items.

When such items exist, one of two things is likely (but not guaranteed) to happen. Either the game is balanced around using them and is thus too hard if the player runs out or neglects to do so, or the game is balanced in absence of them and is made far too easy by their introduction. It is certainly possible to design a game in which they are an asset, but too often they're included just because it's 'one of those things that one does' in an RPG.

To a similar degree, this issue exists with Buffing/Cleansing Consumable Items too. While Healers often suffer a lack of respect, diffracting their skillset into various consumable items just makes it more of a pain to balance, though it can be done to varying degrees of success (See: Every Pokemon game ever).

Next, I'll take a look at equippable items.