People support a winner, pretty simple. If the men's team starts winning, they'll get more support. But when the university itself doesn't care, there's no way the fans will.
Nebraska is also a Volleyball school, and fan support here is among the best in the nation, with only Hawaii putting more butts in seats over the past decade than us (although look for that to change when the team moves to the Bob).
We've had some awesome fan support for baseball when they were playing well, but the last few years have been pretty dismal, and support once again fell off.
Football does reign supreme in Nebraska, and that's not likely to ever change. But other sports could make their own noise.
As far as the site goes, we've had subforums for other sports (most notably Volleyball), but traffic to those other forum isn't always high, so when we redesigned the board a couple of years ago we axed the individual sports forums. Maybe if/when interest builds we'll bring them back.