Whenever a discussion about raids starts to get a bit more heated, the argument of "you just want more epics" gets tossed around. Hardcore raider leaving his old guild to join a more advanced one? "Just wants more epics". Casual raider arguing that raiding should be more accessible? "Just wants more epics". Someone in guild chat complaining he didn't get a raid spot? "Just wants more epics". This often repeated argument gives epics a bad name, and leads to even more derogatory terms like "welfare epics". So everyone claims he isn't doing whatever he is doing "for the epics". Only that isn't true. Epics are an important part of the raiding game. Not to strut around with in front of the auction house, but as entry ticket to further raids.
The larger part of most raids depends very strongly on the numerical stats of the participants, not their skill. Yes, there is skill involved in learning how to react correctly to every special ability of every boss. But the better your stats, the easier it gets to get it right, and the better are the raids chances of survival if things go wrong. The abilities of Moroes and his henchmen in Karazhan are still exactly the same as they were when TBC came out. But his health got nerfed, and many raiders visiting him now have much better epic gear than the first time they met him. So suddenly you don't have to set up crowd control for every henchman up, you just put the skull raid mark on the one who heals, and AoE the others. Moroes's Garrote still does the same damage as before, but due to epics players have a lot more stamina, and survive it a lot easier. And due to epics the damage output of the raid is generally much higher (and, as I said, the mobs health has been lowered), and the fight is over sooner.
Special abilities of bosses aside, a raid combat isn't significantly different from any other combat in WoW: The players' dps is measured against the mob's health, while at the same time the mob's dps is measured against the players' health and ability to heal. As epics increase the players' health and dps, they automatically make the fight easier for the players, and increase the chance of the raid to down the boss. A guild advancing through the raid circuit from one boss to the next, and from one raid dungeon to the next higher one, is not just due to players learning the boss encounters; it is also very much a function of the players equipping themselves better, and everyone having better epics.
So of course everyone who wants to raid will want epics. They are his ticket into the raid. Without a certain level of gear the player will not be accepted into the raid group. For the casual raider being invited into a raid means not only that he'll learn the encounters better than he possible could by reading tactics on some website or watching a YouTube video; it also means he'll end up with some better gear that will enable him to be more useful for a future raid. The hardcore raider who feels he needs to leave his guild to advance further is not just frustrated that his guild is getting past raid dungeon X, he is also stuck because he already has all the gear from dungeon X, and needs to visit dungeon X+1 if he ever wants to have a chance to see dungeon X+2. Even the best raiding guilds in TBC all had to start with Karazhan and follow the same raid circuit from there to Sunwell Plateau. Without the right epics, visiting Sunwell Plateau just won't work, even if you are a great raider.
And this is the reason for much guild drama: If you don't get invited into a raid in the first place, or you participate but don't receive the epics, it becomes even harder for you to get invited into the next raid. Every guild has different rules, and some even rather complicated DKP systems, on how to distribute raid spots and epics. But no system is perfect, and none removes the fundamental problem of whether it is better to concentrate the epics in the hands of a few, who will advance faster, or whether it is better to distribute them as widely as possible, to make raid attendance easier, and thus more widespread and stable, but slow. Giving somebody epics opens access for him to harder raid dungeons, but that access is a personal one, and there is a risk that the receiver uses that entry ticket not in the guild he is currently in, but in the next one. Concentration of epics, quite often in the hands of a main tank, can propel the whole guild forward, but also set them back significantly if the MT defects.
Badges help to spread the rewards. But Wrath of the Lich King also introduces one BoE epic on the loot table of every raid boss, which has certainly advantages, but also a huge guild drama potential. Do you give it to somebody in the raid for whom it is a minor upgrade, or to somebody who wasn't in the raid due to lack of equipment, enabling him to come next time? Some guilds might even have rules in which regular raiders not in the raid have priority on BoE epics over casual raiders in the raid.
In summary, epics are important, as they give access to more raid content. And it is often the raid access people are after, not the epic itself. What looks like a petty squabble over loot might well be a much more fundamental argument over the opportunity to participate in guild events. And what looks like a simple problem of rewarding people for their raid participation by handing out epics can well lead to problems with raid participation in the future. If you can't get a raid full, are the other players in the guild unwilling to help, or are they simply unable, having never received their entry ticket of epics?