It's that lack of having an appropriate spec for most encounters that is such a hard blow to us as a class. Going back to our beloved DK's, if a fight prefers sustained dps they can always spec into Unholy. If it's switch burst or burst of any kind, Frost will do the job AND THEN SOME. Frost even works both ways, it'll also handle well in sustained fights, so preference actually becomes an option, to a certain degree. And this is a hybrid class, mind you.
Rogues? We have nothing of that sort. At least Sub had the potential of becoming OUR Frost spec. On live, at the end of Cata, Sub actually has some good burst in its Backstab, especially if Find Weakness is applied. But now that Eviscerate is our "new Backstab" even Sub has just become a clone of Combat. I hate to repeat myself, but we need some clear roles for our specs and some spec-differentiation.