Esports aren't about skill anymore. Halo wasn't an Esport for years because it was a demanding and rigorous game. Esports are about money and commercial opportunity. This is becoming more and more apparent as the industry - and money involved - grows over the years. The corporate sponsors don't care about 'inherent skill'. They care about financial opportunity.
This is why LoL has such a big e-Sports following. SC2 is still quite large, but not to the scale of LoL. I don't see a lot of FPS anymore, it seems to have faded in to the background.