Well IMO you're comparing apples and oranges here.
It's funny, though, I love Starcraft II but for different reasons than you. I never even finished the Wings of Liberty campaign, and didn't even bother starting the Heart of the Swarm campaign. I found the story to be pretty ridiculous and the characters pretty boring. I love StarCraft II for the online multiplayer--i.e. I play it as an e-sport.
You say Starcraft isn't deep, and to be fair "deep" is a pretty nebulous term, but I'm not sure why you think that. The metagame has evolved a lot over the years as players find new strategies and then find counters to those strategies. If you watch a video like
this one you can see how much some of these grand masters players have to know to play at that level. You need a ton of experience and knowledge of the game and meta-game to be able to read opponents successfully, let alone to be able to react successfully. But to be fair, until you get to masters league, that kind of stuff isn't as important as basic macro, which is less about strategy and more about training your hands and brain to multitask well.