I used to watch tons of Starcraft, but I feel like at least half the reason was to find inspiration for new strategies and playstyles whenever I got bored of playing standard. For example I pretty much never watched the matchup between the other two races I played.

Whereas I feel like the same can hardly be said for traditional sports. I don't see how you gain any strategical insight into the game of soccer by watching the world cup, at least on the level that a normal viewer could implement.