Okay, let's be serious, this is actually a fairly decent (and convenient) change. Is it absolutely needed? No, not at all, but how many of us carried around Simple Wood and Flint and Tinder at all times? Who took those things to raids with them? Very few people, if anybody at all. And I can recall tons of times that people have rushed to a raid just after getting home from work and had forgotten to cook up their consumables. These fires would've been legitimately useful right then, but the small annoyance of carrying stacks of Wood around made it pretty unlikely that anybody had them. Nowadays, I think just about everyone carries a Gnomish Army Knife (and they should if they don't), so this is actually very convenient! You don't need to carry anything extra at all.
My question is... what are we burning to make that fire now? Sure, if you're out in the wilderness you can just assume your character gathered some firewood, but you're not always in a position to do that! What if you're in the middle of Ulduar? Pretty hard to burn all of that stone, isn't it? Daniel Whitcomb suggested that his Death Knight will just summon a ghoul and light it aflame to cook his meal, but that seems a little macabre, even for him.
[Thanks for all of the tips, everyone!]