Still, a small degree of luck ads spice, IMO. Having played thousands of quick online chess games, IME, unless someone plays a fairly unusual opening, most games quickly become similar in nature. Yes, there are subtleties arise that are interesting and keep the game flexible, but the simple fact that GM's (and others) can plan their first 20+ and play them in under a minute (primarily a time-saving device). In fact, when Spassky played Polgar (World's highest ranked female, at least at the time), Black (I can't remember which) mained a ridiculous error that would have lost them the game immediately by transposing two moves (move ~15). Neither player noticed and the game continued normally. Don't get me wrong, I love chess (as well as other "pure" strategies like 'Chinese Chess' and 'Go'), but they all have that element of predictability. This can be good and bad, of course. Beyond that, there are many brilliant games that are almost pure strategy yet have small degrees of luck. Sometimes in A&A you lose your battleship (even if it has two HPs) to some pissy sub on the defense. It would suck, but it's very unlikely. That's why you don't just bring the Battleship, you bring the fleet
EDIT: Oh, and I disagree that WC and SC are "pure" strategies. They are certainly not on the same level as chess, at any rate. In fact, I would generally call them tactical games. Yes, there is some strategy involved, but it's not too hard to learn the most effective build orders generally. The best players are the ones who can do these ordes effectively and efficiently, IMO. YEs, every once in a while a tactical genius finds something revolutionary, but at this point if you visit SCU you can pretty well play the game as well as anyone. The same cannot even be said for Civ, IMO, let alone chess.