I actually disagree here.
Blizzard has indirectly told every player how to DPS.
Well, not told them how, but set up an efficient rotation. As a DK, you can make up your own rotation, but your runes will be all over the place unless you use them in a specific order, and only dump your runic power at specific times. As a prot warrior, if you don't follow the priority system, your threat output will suffer. As a hunter, if you use the wrong shot at the wrong time, you'll do less damage. If an Arms warrior refreshes Rend at the wrong time, he loses an Overpower proc.
I don't deny that it's possible to freestyle it a bit and still get good results. But the fact is that there's always a mathematically superior option (although that can vary for some specs based on gear).
They're not trying to make every rotation viable. They're trying to make every spec viable.