Unclean: Thats not right. If I could take Starcraft and Age of Empires as two etalons of RTS (well, others are realy uninportant, such as warcraft 3, I was talking about RTS, not RPG), in both building placement is REALY important. As you are not just using chokepoints, you are creating them. As in later game it not may be in mutch importance, the effect in early game is huge, as you could defend with lesser ammount of units and thus boom more.