Perhaps a deeper explanation of the raider mindset when it comes to loot rewards would help in our discussion on PvP vs Raid Epics. Please note that this is strictly from a Loot As Reward perspective, not Loot As Investment.
For a raider, quality of loot depends on the challenge you need to overcome. The harder the challenge, the higher quality your reward is. Quantity of loot does not really change. Throughout my raiding career, I've averaged about one epic every two weeks or so. It is random, so it's not exactly one every two weeks, but it's close. The rate at which a progressing raider gains upgrades doesn't really change as content changes. What changes is the quality of the upgrades. As the raid gets better and better, as harder and harder challenges are overcome, raiders are not rewarded with more loot, they are rewarded with better loot.
So in the raider mindset, quality is the most important characteristic of loot. It represents the challenge that has been overcome. Raiders generally don't like content where the quality of reward does not match the challenge. Even bosses which are too easy for their loot are disdained (Void Reaver, most of Molten Core). Bosses which are too hard for their loot inspire a lot of forum angst.
This is diametrically opposite of the PvP situation. In PvP, the quality of the reward is fixed, and is generally whatever the highest season is. What changes is the quantity of loot. Higher skill or rating, which translates into overcoming harder challenges, is rewarded with more loot, not better loot.
From a raider mindset, this is very weird. It breaks the link between challenge and reward. And we like that link. Raiders feel that having that link is important, as it inspires people to push forward. If you don't get better as a raider, you stop progressing loot-wise. In PvP, it seems like you don't the same pressure to improve your skills. You stay level, and the loot keeps coming in, and you are able to improve your character without improving in skill. Sure you could get the loot faster, but the upgrade train never actually stops or even slows down.
Raiders actually like PvP rewards that match the "challenge = quality of reward" mindset. People with the epic flyers, or the various titles, are impressive. People with high ratings get a lot of respect.
And it's an honest question if a game should break the link between challenge and quality of reward. I kind of like that the game pushes you to continually increase your skill. I would love 5-mans or solo quests that continued to increase in challenge. Zul'Aman has been highly received by the raiding community, even though it's only a 10-man. Many pre-TBC hunters still speak fondly of their quest to get their epic bow Rhok'delar, as it was supposed to be a very challenging quest.
When the game doesn't have that push, we end up with negative behavior. We have people AFK in Alterac Valley. We have teams /dancing in Arenas so that they can finish their games quickly.
Raiding does have many problems, especially with time and organizational issues. But the basic idea that "quality of reward is linked to the challenge overcome" is not one of them.