Alaric.us: That was how RTS games were at that point. I think Starcraft became the first truly asymmetrical game, and that is one of the reasons for its immense popularity. Before that, the differences between factions were always either cosmetic or otherwise very minor (Dune 2, Warcraft 1 & 2, etc.)
CARRiON-XCII: GDI and the Brotherhood of Nod would beg to differ.
I always felt that C&C factions weren't all that different. No more so than the factions of Dune 2.
Naturally, they were not exact reflections of each other, but overall it was pretty much the same thing. NOD/Atreides cost a bit less and made a bit more units that were a bit weaker. GDI/Harkonnen were a bit more expensive and made a bit fewer units that were a bit stronger. In the end you still made a bunch of little cars and sent them at the enemy. It wasn't entirely different play styles like, say, Zerg and Protoss.