Also, at least in my opinion, the very limited nature of the total set of states relative to the total set of states in something like an RTS lends itself to repeat engagement and analysis. You can, and likely will, see exactly the same board position in more than one chess game. You almost never going to see exactly the same game state in multiple SC games. That changes the dynamics of post-game analysis and skill development, IMO.
(Don't get me wrong, I enjoy both- but I do enjoy them differently.)