Quote: "rts's you actually have to think on a much wider scale controlling an army not just a single character, and then designing your base for max security etc."
Yes, but the missions themselves are almost identical.
Almost all of Command & Conquer's were the same damn thing.
Wipe out the Enemy Base.
Yet what made the game interesting, was the units you had, the units the opposition had, etc. As I said, it isn't the missions but how they're setup that makes them good.
Most of Guild Wars missions don't play the same. You had new things happen each time, and more often they were multi-part so you might have to protect someone in one mission, then take that item to someone else, who uses it so that you can kill a boss.
It sounds simple, but the way it's integrated as either a sub-story or a self-contained story. Makes it feel much more involved.