Urban Meyer saw several advantages in taking the Florida position, and when it came down to it, the prestige and honor of being ND's head coach were dwarfed by the benefits and perks of being Florida's head coach.
1) Florida was very well stocked with 4 and 5 star talent. The previous coach, Ron Zook, wasn't a good head coach, but he was a proven recruiter (hell, he even had success at Illinois as a recruiter), and the depth chart was stacked with future NFL draft picks.
2) Notre Dame had two full recruiting classes that were decent (2002 and 2003), along with a handful of 2001 holdovers. Beyond that, we had two of the absolute worst recruiting classes of all time in the way of 2004 and 2005. 2005 would have been much worse if Charlie Weis didn't make some last second recruiting bids for some decent players (Duncan, Turkovich, and I believe Kyle McCarthy were all part of that last ditch effort). Meyer knew that in 2007, things were going to hit rock bottom, and he wanted to win championships instead of trying to rebuild.
3) Florida gave Meyer total control over the football program. Notre Dame's Board of Trustees wouldn't allow for it, nor will they allow for it with any future coach.
Even Urban Meyer would have had a nearly impossible task of getting us to a .500 team in 2007. There was no way we were going to be able to compete with Tyrone Willingham's awful recruiting classes, since a lot of them (especially in that 2004 class) either quit or transferred. Without developed juniors and seniors, you're not going to beat teams that have decent developed depth, plain and simple.