Reading through the comments on a recent WoWInsider Encrypted Text article I saw a similar sentiment expressed by a lot of players, “Rogues are just generic mDPS.” This isn’t the first time I’ve seen this sentiment, it pops up quite often on various forum posts but this time I saw it I started thinking about why this sentiment is so common when in my experience it is simply not true. The answer I believe is an issue of level of play, the exact things that have opened up raiding so well to casual players have resulted in this sense of homogeneity. Before I go further I quick note on the use of the word “casual,” I’m not a fan of the word in general, it has too many definitions to be broadly meaningful, in this post I am using it as a convenient shorthand for flex, normal and lower progression heroic raiders who do not min/max their raid comp.
“Bring the Player not the Class” was the watchword of Wrath of the Lich King and almost every mention of class balance brought up the ugly acronym “BtPNtC”. Blizzard mentions BtPNtC much less now, primarily because it worked so well. While I would be a fool to claim that class balance today is perfect, the degree that classes are balanced to today is incredible even from the perspective of late Wrath. There will be misses occasionally (Hello Destruction Warlocks) and questions about how BtPNtC applies to high-end heroic progression but overall Blizzard succeeded. Left unsaid in many of the discussions of BtPNtC is how it enabled the other major Wrath philosophy change, casual raiding.
The link between the two is obvious in hindsight, casual raiding, pug raiding and the new hotness of flex raiding basically require raid comps to flexible where one a melee dps is a melee dps and a healer is a healer. To be sure certain dps may be better for one encounter or another but the encounter is balanced such that groups don’t need to care about those differences. Lets consider flex style raiding because come Warlords flexible raiding is going to be what most people experience. Flex is built around a simple idea, the raid must go on, if someone can’t get online, the raid must go on, if someone has to leave early, the raid must go on. It isn’t perfect, a tank leaving is still a problem but flexible raiding loosens up comp restrictions about as far as they can go while still preserving the basic concepts of raiding and the trinity.
It should be clear why BtPNtC is essential to flex, BtPNtC allows raid leaders to think of people in terms of their role, with skill and gear being deciding factors about whether or not to bring someone rather than having to think about their classes. It wouldn’t be an exaggeration to say BtPNtC at a high level turns players into roles rather than classes. This brings us full circle, the reason many rogues feel like generic melee dps is self-apparent, the design of raiding today requires it. The question casual players need to ask themselves is not “Would you like less homogeneity?” but rather “Would you be willing to give up flex raiding in exchange for reducing homogeneity?”
I try to end my posts on a positive note, if I identify a problem I like to at least point in the direction of a solution, here I have nothing. The conflict between casual/flexible raiding and class diversity is fundamental and in many ways built into the underlying design philosophies Blizzard has been pushing since Wrath with great success. When I first started thinking about this I called it “Blizzard short-changing casual raiders” but I’m not sure that assessment is accurate. Blizzard looked at this seemingly intractable conflict and deemed access to raiding more important than class diversity and I suspect a large portion of casual raiders would agree.
Rogue Chat 
This is a thoughtful piece and an interesting topic. As you point out, because of the necessary flexibility of the current design paradigm, Blizz has had to design for melee, rather than rogue or warrior etc. – or worse, for DPS regardless of range. This limits not only class design but also raid design. The upcoming Mythic raiding format gives them the opportunity to fix this and design for the class not the role. It will be interesting to see how much of this will trickle down to the more flexible formats, Normal and Heroic. LFR will need to remain pretty generic to accommodate the random group formation. But maybe with a little luck, Normal and Heroic (along with Mythic) will start being able to think about Bring the Player, not the Class AND Bring the Class, not the Role. Diversity may become an advantage and the raid sizes will accommodate that. From there, we will be able to diversify the classes more again. Hopefully this will be progression and not just bringing us back full circle.
Letting these mechanics trickle down would be disastrous to the raiding model Blizzard is trying to create. “LF Rogue for Raid X on Boss Y must know how to do Mechanic Z” is the exact thing that flex cannot be. As I said above the big idea of flexible raiding is minimize the number of possible things that could prevent the raid from occurring. If you need a rogue for an encounter and your rogue isn’t on, or perhaps you don’t have a rogue on your roster at all you should still be able to raid without having to waste time sitting in trade chat or the cross realm raid browser spamming for a rogue.
Additionally I don’t think mythic is going to change the current raiding paradigm too much. Heroic raiding already has some pretty strict comp dependence on challenging fights and I expect that to remain true on mythic. I may not have made this very clear in the post but most heroic raiders have a pretty good idea what makes their class/spec desirable in raids because we are pretty well acquainted with having to sit on bosses where there are simply better options. Heroic raiding comp dependence hasn’t generally trickled down to lower difficulties because that would work against Blizzard’s intended design and I see no reason why that will change in WoD when Blizzard puts even more eggs into the flex basket.
Yes, absolutely, if implemented restrictively, trickle down would be disastrous and completely counter to the paradigm that Blizzard is working towards. That said, they have been working in dynamic mechanics over the last few raids that would allow them to develop some very specific requirements for some difficulty levels and allow them to loosen them for others. For example, on one difficulty level they might require you to have a specific class to perform a task, on another they might adapt the task depending on the class of the person set to perform it. We’ve already seen tasks based on timing and on role. If they ratchet down the parameters they could produce some really interesting encounters while still accommodating random groups.
Re Mythic, yeah, Mythic probably won’t change things too much, except that they have said that they are going to assume diverse compositions and will be able to design accordingly. This will give them a lot more leeway for interesting encounters. Hopefully heroic raiders will be able to play more and sit less…but the best laid plans of mice and men…I guess we’ll see how it plays out.