I'm sure ESPN broadcasting WNBA games is part of the overall contract they have with the NBA. They aren't trying to prove a point by showing WNBA games, it's more of them being required to broadcast by the agreement they have with the NBA. ESPN wastes plenty of hours of broadcasting the Little League World Series, as well. They have hours of TV they need to fill, and it's just a dead time in sports right now. Other than baseball, there is nothing else going on, and ESPN decided a few years ago they don't want to be in the MLB business.
Also, if ESPN broadcasts a Nebraska game, or any other big college football or basketball game, you refuse to watch it?