OK, I guess I have to state a contrarian opinion here...
The XL Center absolutely is a more important focal point as a facility than Gampel. It's a cash cow. I'm a rare exception to this because I'm equidistant between Hartford and Storrs, but the Hartford MSA has 1.2 million people (or about a third of the state's population). If you are one of those people, wouldn't you prefer to go to a game in town than drive 45+ minutes to Storrs? And what if you live in New Haven Country or Fairfield County? Storrs then becomes even more of a trek, whereas Hartford is readily manageable.
Meanwhile, the XL Center has the capacity for huge attendance- far more than Gampel. 16,249 people came to watch UConn beat Florida State for its 89th win in a row (yes, including me). Same with Baylor in 2013. Had the games been at Gampel, attendance could only have been 10,100. In other words, XL may not always sell out, but it can fail to sell out and still seat more people than would even be possible at Gampel.
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Finally, alcohol is readily available at XL. Again, it's a cash cow.
In summary, location is critical, and XL is a better location for the critical mass of Nutmeggers. If you want to drink booze while you're at a game, you can. If you want to eat at a lovely restaurant (think Trumbull Kitchen or Feng) before or after a game, your options are far better then the mediocre food court at the UConn student union. Finally, if the game is a compelling matchup against a highly-ranked team, more people can come to the XL Center than can go to Gampel to watch it.
The XL center is the more important arena. I don't think it needs to be massively renovated...unless, of course, the cash cow is losing its ability to be effectively milked.