You also need to consider the fact that we're talking about a very small difference here. Yes, there's a lot of space between the first couple of specs, but after those, ret is not far behind on the rest. The first classes are overpowered. The ones close to each other are balanced. Someone's gotta be last though.
Next up is Raidbots. Looks shiny and all, but I still believe Blizzard's method of testing is far superior to logging DPS of a bunch of specs that ALL contain RNG. You get lucky, you do more DPS. easy as that.