This has been the case since vCOH. Higher rank often equates to more abusive and less creative strategies to get there. COH does not reward you for playing "fair", you either fight fire with fire or you'll lose more often.
I don't think any RTS, hell any competitive game for that matter, rewards you for playing fair. If it works, you use it, no matter what. Some players have more or less scruples than others, but not a lot of people who want to be number 1 will choose to use more creative but potentially weaker strategies consistently. They will have the odd game where they do something wacky, but usually they play to win. That's probably as true in Starcraft as it is in CoH.
I mean, to use a recent SC2 example, loads of people hate the Swarm Host unit with a passion. Doesn't stop top Zerg players from using it if they want to, from what I saw.