You could say that only the highest level raiders are going to be that worried about making sure that they have every single buff they can have, but even as a casual raider, I've found a lot of use in buffing as many ways as possible. Unlike the really epic guys (who use food, potions, and elixirs to beef up their already awesome gear), I tend to use potions and food to cover my weaknesses. For instance, I don't have as much +hit on my gear as I should have, so I specifically carry around hit food at all times, and I can see the results in my DPS. Even if you don't have the best gear, using the right potions and food buffs at the right times can help you drop bosses and win fights you normally wouldn't.
Of course, that seems obvious to min-maxers, but many raiders with less experience don't realize how much of a difference the right pots and food can make on the raiding game. Lots of these buffs are cheap to buy (and even cheaper to farm if you've got the professions), so if you're raiding with regularity, definitely take a look at your stats and see if you can't throw a few temp buffs in the mix.