I'm going to agree with Chick. The thing is though, sometimes it's nice to have just the basic, fundamentals, and if they're polished to perfection then it can work out. It's like Starcraft 2 is the paragon of basic RTS gaming, potentially, and because that now exists, other game developers should now implicitly be encouraged by its existence to try to innovate in RTS so that they don't have to compete against Starcraft 2.
The other problem is, those "innovative" games are often bug-ridden, balance problems, or lack other complex depth. For all its simplicity, the tactical depth of Starcraft 1 was done really well without the shtick that passes for balance in a lot of other games. A lot of other games (like Command and Conquer series) will give certain teams dominance over certain aspects of the game - giving one team air superiority, one team armor superiority, the third infantry superiority or whatever. This kind of balancing forces players into one kind of playstyle, which is boring and (haha) one-dimensional. I don't know about professional starcraft (since I abhor the concept), but at least in my experience I've found it necessary to, regardless of race, have combined-arms mixed formations of troops. It's not just "spam tanks, rush," it's "okay, need zealots, need dragoons, need air support, need detectors, need templars..." Sure, you can try to just spam one unit, and sometimes it works (marines, hydralisks, zealots. battlecruisers?), but it won't work as effectively.
And therein lies my issue with supcom. It's "spam highest tier, go" because of the way the tier system works with higher tier units being strictly better than lower tier units, and no way to upgrade lower tier units to keep them competitive. In this sense, I think Supcom 2 worked out okay with its research system, but it too lacks depth in that it has like, 3 types of units total. More defined roles for its units + more variety would've been great - interceptors vs. air superiority fighters (interceptors to race across the map and shoot down that experimental before it gets to you, air superiority slower but more maneuverable and longer airtime), the tanks vs assault bots balance being less "this one has health, this one does damage" (which is ridiculous because assault bots are autopositioned in front of the tanks, where they shouldn't be).