If anything, it gets in the way more because the textures and shadows start to screw with your ability to properly target air units.
I definitely prefer an RTS with simple graphics. Makes it easier to tell the difference between units.
--------------------------------------------------------------------------- I don't want a big car, particularly. I have no need for acreage, and I don't like the fuel bills. But I don't want a small one because they're all like supermarket own-brand cola: weedy imitations of the real thing - Jeremy Clarkson