This. He gave them seven years to build a team around him and they didn't. He put them on his shoulders and carried them all the way to the Finals but he just couldn't do it by himself. Lebron WAS the Cleveland Cavaliers. They had a chance to trade him but they didn't so he walked.
Jordan on the other hand...they built a team around him and gave him plenty to work with. All the years he tried to carry them to a championship by himself he failed. When they put a good squad around him they won it. Think about it...how many championships is Jordan famous for winning on his own...none.
EDIT: Think about it...Jordan and Pippen, Magic, Worthy, and Kareem, Shaq and Kobe, Shaq and Wade, Stockton and Malone (even though they never won one), The Big 3 in Boston, and later on Kobe, Bynum and Gasol. The list goes on.
GREAT teams don't have one guy. I'd rather see Lebron go somewhere else and get a ring or two than suffer the fate that Dirk has (try and try and try and try and try with no help). That'd be a HUGE waste of talent.