Read this comment over on WoW Insider, and thought it does a pretty good job of summing up one angle of the anti-Arena perspective:
Terrible changes. This is what I posted to my raid's forums (and yes, we're high-end raiders working on Sunwell):
I think comparing PvP rewards to PvE rewards is ridiculous. You don't fight other players in the Sunwell, so it doesn't matter how strong your gear is compared to what other people are wearing. It does, very much so, in PvP and according to this system the "rich get richer". Those who already have the perfect spec and the perfect class and the good gear and the perfect team setup (which means being unable to play with friends more often than not) now gain even more of an advantage over the people who lack these things. If the gear was only usable in the arena and people were in the brackets were they were supposed to be it wouldn't be that much of an issue, but when 30% (or more) of the arena games you fight at 1600 rating are against people in full s3 who are supposed to be at 2100, it suddenly matters a -lot-. And that's not getting into the effect on battlegrounds, which is pretty ridiculous already. My ret paladin, who is in mixed S1/S3 gear with very few of the honor rewards, -destroys- many people in the battlegrounds. It can't be much fun to be a fresh 70 and unable to do much of anything.
The point of the arena system was to limit the gear gap in pvp by letting everyone have a chance at the good gear. The reward for being good was getting it much, much faster, and having a shot at the end-of-season rewards. The mistake Blizzard made was making the gear so ridiculously good it upset raiders who based their enjoyment of the game on comparing the arena gear to the gear they get from PvE encounters (yes, an over-simplification, I know). Now people are focused on ilevels and trying to prevent people from having the same quality gear they do because of pride without ever really considering the impact restricting the arena gear has on the game.
Blizzard really destroyed any semblance of PvE/PvP reward balancing by their insane item inflation. That's fairly well established. Trying to balance it at the end of the Burning Crusade serves what purpose, exactly? People already have ilevel 141 epics, what's the point in restricting ilevel 151? All it does is upset the people who are into pvp and have relied on it for personal character progression, but are unable to make it to the higher ratings for some reason or another. And what many skilled pvpers fail to understand is if you take away the incentive for lower rated players to participate, the entire arena ladder shifts down. If 1,000 players who were previously at 1400 rating quit the arena because there is no reason for them to play, then 1,000 players who were ranked above them will shift down to 1400, making the higher ratings that much harder to obtain. If the players who are NOW at 1400 quit playing, then another 1,000 will shift down. And so on, and so on.
All in all it's a terrible decision. Blizzard messed up so badly with the arena for Burning Crusade, that they're trying to "balance" the rewards now when it's already way too late for BC is nothing more than a bad joke.