the mod community for XCOM has been very active and for the most part the developers don't try to stop them. If anything features in the next version of the game show a lot of requests for what previously had to be modded are to be added.

With regards to eSports and the sites that cater to them, I would like to see them impact on game sales as well as the hardware used to run them. If anything watching others play a new game is a great way to determine if its even worth buying