I used to be a huge college fan. The college game definitely has some things that make it good IMO.
The loyalty. I think people who attend a particular college feel a lot more connected to the college, than people who live in a city where a professional sports team is played. Also look at the followings. How many Celtics fans travel to different cities for playoff games? I've been to the Big East tournament and the first 2 rounds of the NCAA before. You have tons of fans from all over traveling to support their team, you don't see that in the NBA (and I'm not talking just college kids, I've probably seen adults do this just as much). If you're not a sports fan and grew up in Boston and now attend BC, I think you feel a lot more loyalty to BC then the Celtics. You'll always be an alumni of your school, you don't always have to be a fan of whatever professional sports team. Which helps lead to the energy.
The Energy. Nothing beats the crowds at the home courts for those with teams with the most loyal followings. Even watching on tv you can just feel the energy, especially at a big game. Flat out, crowd energy makes a better experience. An exciting game in an empty arena, it's still an exciting game, but that same game in a packed arena with the crowd going crazy takes up the viewing experience about a hundred levels higher. Even if your team stinks, the current students will keep the place rocking.
http://www.youtube.com/watch?v=a2C-dL1lLpIhttp://www.youtube.com/watch?v=30m0UNTz9hoThink how much cooler a Celtics game would be if EVERYONE dressed in green, and the crowds got this crazy.
The Rankings/Polls. I think the drama with the rankings/polls helps make the game exciting. Who will be #1 this week? How many spots will Team X fall after their upset loss? Even though the polls doesn't really determine anything, it makes it more exciting. The NBA on the other hand, nobody really cares too much about the standings. Oh the Bulls overtook the Celtics for first in the East, San Antonio has been #1 for X straight weeks. Nobody really cares. The closest we get to this is somebody's power rankings.
Every game matters, anything can happen If one of the top teams in the NCAA loses any game, conference or non-conference, it's a big deal. If the Celtics, Lakers, Spurs, etc. lose a January game to the Raptors, it's an afterthought. Plus the single elimination conference and national tournaments mean you can't really afford to take a game off. Anything can happen.
I think these are why people are so into the college game.