On one hand, you could argue he has a point. Homogenization has long been a complaint of the playerbase at large, so people like having their differences in specs and classes. In addition, with all these major secondary stats, one of them needs to be lower than the others, and some of them have to work differently for other people.
That said, there are counterarguments to be made here that merit some consideration. The biggest one is that there is a difference between flavor and function. This is especially apparent in the argument for unholy AoE damage. Certainly, you can argue that unholy's style is that of a thousand little cuts -- lots of damage sources such as diseases and pets that add up to big damage over time. On the other hand, the need for burst damage is a demonstrable part of the game. Sometimes, doing damage over a long period of time just isn't feasible. In cases like this, unholy's lack of burst AoE isn't a quirk of the spec -- it's a genuine disadvantage in that they cannot put out damage when it's needed most.
We can make a similar argument for the problems that unholy has with mastery and frost has with critical strike damage. It's true that undervalued secondary stats are not the end of the world, but the problem becomes when those secondary stats don't even give you much in the way of help. Pets are a large part of unholy damage. If mastery doesn't work on them, then equipping gear with mastery on it in itself makes you feel weaker.
Consider it rather like gear with the of the Whale suffix (stamina/spirit gear) back in vanilla WoW. Everyone avoided it like the plague, and it was the laughing stock of the community. It wasn't that spirit and stamina didn't have benefits -- they did -- but those benefits were so minuscule that you were always better off wearing something else.
The same is true of mastery gear for unholy death knights. When an unholy death knight feels forced to wear a mastery-bearing piece of endgame gear, it may not be actively weakening them, but you can't help wistfully imaging what could be if that mastery was more useful. A similar thing happens with critical strike rating for frost. It's not that the stats are useless; it's that equipping undervalued gear because of them can feel discouraging and certainly means you do not get as much use out of a piece of gear as a different class or spec might.
Presences: As present as they need to be
The exact function and power of the two DPS presences has been a huge controversy within the death knight community, as we've discussed before. The reduction of runic power generation measures has seen Frost Presence's extra runic power become mandatory for dual wielding frost. At the same time, the global cooldown speed of Unholy Presence would keep their rotation flowing smoothly if they could only generate enough runic power. As a result, there's been a big push to make the 1-second global cooldown from Unholy Presence a baseline part of the death knight class.
Ghostcrawler seems to have turned that down, instead establishing the system as staying in place. If you want to use Unholy Presence, you have to use a two-handed weapon. In addition, he said he doesn't want DPS feeling like they have to stance dance, so that would be something that would be fixed. On the plus side, we at least know what's intended by the development team and can test accordingly. On the minus side, there's going to be a lot of dual wielding frost death knights who are going to have to get used to a new paradigm.
Overall, the tone and content of Ghostcrawler's answers was not encouraging, as the death knight community finds out that a lot of things it sees as problems the dev team sees as features. Time will tell how this all pans out, but I think our best hope right now is to hope we can get in enough testing time at level 90 (maybe even in a raid or two) to show Blizzard how these issues are actively holding us back as a class.
Army of the Dead gets its groove back
That said, it's not all doom and gloom in death knight town. We did get some pretty interesting and fun changes in some of the latest beta builds that are worth looking at. On a balance note, Unholy got a much-needed bone, as Sudden Doom now reduces the cost of Death Coil to 32 runic power, something that should make our rotation for that spec a lot smoother. In addition, Glyph of Unholy Frenzy now makes said ability a little less deadly, removing the health drain. In what should be good news for a lot of old-school death knights, Glyph of Corpse Explosion will give you that classic ability back.
Army of the Dead is the other skill under the microscope right now. Ghostcrawler has said there is room for a buff, and while it still remains relatively weak on beta, they did finally add a long-needed minor glyph that lets you remove the taunt and another that lets it summon various types of undead. Of course, we're still waiting for a buff to the damage of the skill itself, but we'll see how that goes. With the 10-minute cooldown, it's unclear that it will ever be able to fit into your average damage rotation, but it might be nice to see it at least worth breaking your normal damage rotation to fit it in.
Learn the ropes of endgame play with WoW Insider's DK 101 guide. Make yourself invaluable to your raid group with Mind Freeze and other interrupts, gear up with pre-heroic DPS gear or pre-heroic tank gear, and plot your path to tier 11/valor point DPS gear.