I'm inclined to agree. At least, to a point.
There are extremely bad eggs in every race on Azeroth and, in the case of the orcs, it just so happens that one of their bad eggs is currently running the show because of the lack of foresight or perhaps guilt of one of the supposed good eggs. When bad people are in power, they tend to surround themselves with equally bad people, sadists, megalomaniacs etc, so what we see of the orcish hierarchy is often bad at the moment, but seeing as how orcish society is not democratic, this does not reflect in any way on the majority of the orcish populace, who, I believe, are of the same average moral calibre as Azeroth's humans.
As for the Forsaken, I think that many of their kind are amoral and ruthless, merciless and calculatingly cold in combat, but the vast majority are not actively evil as I do not believe that most are interested in causing unnecessary suffering. By and large, they only inflict as much suffering as is required to win victory (in open war), secure their territory and defend the existence they believe is their right. Sure, their methods are gruesome and brutal, but they're affective and efficient. But, I believe that, for the most part, once they have achieved what they set out to do, they are not interested in taking that cruelness further. That's why I describe them as amoral (lacking concern for morality), rather than immoral (being aware of a concept of what is moral and actively going against it).
Even Sylvanas' objectives do not seem to go beyond securing Lordaeron (and surrounding failed states like Arathor) as a safe-haven for herself and, by proxy, her subjects. She doesn't seem interested in causing suffering beyond what seems necessary to achieve that.