What i hate about Relic is they innovate new army designs for the simple reason of innovating. For Relic its worth it if gameplay takes a backseat as along as new armies are radically different than the older armies. Relic could learn a thing or two from Blizzard when they say "GAMEPLAY FIRST".
Except in WC3 and SC they managed to create completely different armies.
The thing is, blizzard NEVER implemented new armies after initial release of their RTS.