Blazblue, for those who haven't tasted it's sweet fruits, is a very Japanese 2-D fighter with over-the-top gameplay and character designs. To writ, one character is a half-vampire half-antichrist cyborg wizard outlaw anarchist armed with a perpetual motion machine. No, for reals.
Anyway, one of their strengths besides having a unique style are the character mechanics. Every character is vastly different in play style and approach, while still being balanced enough for virtually any character to win a match or tourney. That is a tremendous accomplishment of design; balance is easier to do the more parity there is between player options. It's harder, but far more rewarding in terms of game depth and flow, when some characters are easier to use than others, yet neither one dominates.
The point I'm getting at is WoW comes close to having this kind of balance, yet it falls flat in pursuit of broad-spectrum appeal. Classes are moving into greater balance and viability in Cataclysm, but what's sad is the various classes and specs are moving closer not just in balance, but in difficulty curve as well. Paladins are getting a fancy new resource, while dot classes don't need to worry about clipping and DKs are getting more leeway on their runes. Instead of having a spread of classes, some straightforward and easy, others tricky and subtle, Blizz is pushing the margins in. Which in turn makes classes and specs more homogeneous and less unique.
The concept of flow is that a player is maximally engaged and satisfied with gameplay when the level of difficulty is challenging without being overwhelming. It's also called "the zone" or just that sigh of satisfaction at beating a tight segment. Now, the best flow comes about when a video game adjusts difficulty organically, rather than through a menu. In Blazblue, this is done through the character select menu. Some characters are simple rushdown, others require tricks and mind games to win, and still others use zoning to shore up weak defenses. One of the most intricate characters, Carl Clover, controls two characters at once. And yet, he does as well as a simple rushdown character like Ragna, despite the more complex strategies and execution involved.
That works because some players WANT complexity, and others want simplicity. Blazblue has a spectrum of difficulty in its characters, and WoW needs that too, or it will be boring to some while hectic and stressful to others. The three roles are a good start; they cater to different skill sets, and thus, to different types of players. But in homogenizing the difficulty of the classes, Blizzard is losing an opportunity to provide an organic flow, one of the best experiences pure gameplay can provide. They ought to be an "easy" healer and a "hard" healer (maybe "tricky" healer is better), and yes, it is a good thing that one or two DPSers can faceroll their rotation to success. Some people just like that I guess.
I imagine the majority of paladin players, and warlock players, and so on will like the changes; by definition Blizzard is trying to move the flow of each class to the top of that bell curve. But what would be far more ingenious is to make all specs balanced with the greater raiding environment, yet ensure each class has some say, via their spec choice, on how hard the game is to play. That way, each class had something to offer the outliers on the flow curve: affliction for players who need a challenge to be engaged, destruction for people who just want to press buttons and see high crits, and demonology for those in between. That is a better world, for everyone involved. Including Blizzard.