In addition, a small DPS bonus, along with more health for the tanks and more regen for the healers absolutely matters when a lot of the time, wipes can still happen when the boss is at 2% health or less. In a 25-man raid guild, using the lower stat food versus the higher stat food could actually be the difference between wiping or killing a boss
A 0.2% increase to each person's DPS is a 0.2% increase to the raid DPS. I've seen wipes at 2% or less. But 0.2% isn't 2%. It's a tenth of 2%. 0.2% of a boss's health is one second on an eight-minute enrage timer. And sure, we all have our stories about that one time where the paladin bubbled after everyone else died and killed the boss a second before the bubble ran out. And in situations like those, taking 0.2% off everyone's primary stats might have turned it into a wipe. But those stories are memorable because they're so exceedingly improbable. As I said, it almost never makes a difference.
Situations where that small a buff turns a wipe into a kill are rare enough that you'd have to spend many, many man-hours farming for each wipe prevented.
The .2% number was something that people made up, so I'm not treating that made up number as fact. It's also not just DPS, it's the tank's survivability and the healer mana regen that is also increasing with the use of better food. Extra tank survivability and a reduced chance for healers to run OOM is also important. You have wiped before because your tank died or your healer ran OOM - and with healer mana pool limitations, the extra tank health & healer mana regen is the most important part of not wiping in fights.
Raiders are absolutely 100% required to have the best food, glyphs, gems, and enchants as possible. That's how it has always been. You will see the vast majority of raiding guilds using the highest stat food even if it becomes a burden that takes away from the fun of the game, even if the cost of using that food is higher than the reward you realistically get from it.
It's Blizzard's fault if they make the hard to farm individual food which is only marginally better than feasts, and not the players' fault for being forced by the game to use it.
The fact is that there should be absolutely no difference between the feast & individual food buffs in terms of the stats they give, or it needs to just be easier to acquire the individual food so that it isn't an organizational nightmare to make sure everyone has food. There's no reason to have a marginal difference between the foods because only the best food of any expansion has ever been meaningful. Also, with the way that stats are scaling in Mists, that stat difference is much more meaningful than people give it credit for.