If all races could mind control it would be a different story. If mind control did not extend unit limit, it would also be a different story.
Protoss, already being the strongest on FMP overall, being allowed to use MC, which is stupidly easy to pull off and yields a huge game ending reward, would just add to the imbalances already present.
The way Blizzard implemented mind control was a huge mistake.
Idk dude, on their map T long game has certain advantages that are only really quelled by Protoss's ability to procure tanks. I think MC is fine for them. It's arguably fine for us, but most of our community isn't actually competitive and is completely disinterested in gaining the skills necessary to keep their units and to monitor the map (which is fine, we play this for fun).
I regularly see these pro players beating opponents who used mind control against them. It's not necessarily easy because you've got to have room for the base, money, and time to build up. In an active game, these things don't come easy. And when you do have the time, you were probably way ahead and going to win without MC anyway.
Also I'm sure the fact they only have 40 stacks of minerals helps, too.
