Ghostcrawler responded to several questions (complaints?) about hybrid classes and DPS balancing. His response sheds some light on Blizzards take on the hybrid issue and is worth all players time to read.
Must... not... reply... to... thread....
Then again maybe we need a "pure vs. hybrid debate" forum. :)
Our logic is actually pretty simple. If hybrid classes can do the same dps as pure classes, then why have pure classes in the game? So we design the pure classes to do slightly higher dps.
We try very hard not to define "slightly." I probably got cornered by a bunch of angry posters in a dark alley one evening and blurted out "5%!" Or maybe someone in the forums suggested 5% and it stuck.
Why don't we like to refer to very explicit numbers like 5%? Because look what happens. A fine guild like Premonition or Ensidia posts their Ulduar parses, and players jump on them and say "ZOMG that mage is below the warrior," or "ZOMG that rogue is 7% above the paladin." It just isn't going to turn out that way on every parse, folks. Encounters are very different from each other. Gear varies. Even for fantastic guilds, skill varies. Players have to deal with things like lag or whatever mods they use or just dumb luck. RNG exists in boss fights. Strings of crits for a Fire mage or strings of parries for a DK tank can change the outcome enormously.
Saying that pures should beat hybrids by 5% is like saying a penny should be tails 50% of the time. If you flip a penny infinite times, yes, it will be tails half the time. But if you flip the penny three time and don't get any tails, you shouldn't take the penny to the bank and tell them it's broken.
Our goal is to give every class reasonable raid buffs and utility. None of them should be so good that you earn a spot just because of that utility. Plenty of times, your utility isn't going to be as useful because someone else has already brought that buff. This is by design. However, if you feel your class just got boned in the buff department, that is a great thing to bring up (though probably not in this thread). We used to penalize classes who had excellent buffs. Now we try to spread the wealth of both buffs and dps a lot better.
We want you to get a spot because you know what the blank you're doing, not because your class is programmed to always do top dps or inflate raid dps through a miraculous spell that you impart by clicking a button every 30 min.
Play your class to the best of your ability. If you do so, you will be very high on the damage meters, even if you are a druid, priest, warrior, DK, shaman or paladin. You won't top it on every fight. Some fights are better for some classes than others. Some players have better luck. Over time, the trends will emerge and most raiding players will figure them out. For our part, we will keep jimmying the numbers to get the results we want.
P.S. Don't look for me to address this issue too often, because I have done it a few times now. Dead horse is dead. :)
You can find the whole thread here.