You're correct that casual fans get excited by superteams, and don't mind a total lack of competitive balance.
But as far as putting out a good product for anybody but casual fans, it's a pretty awful model. I'm (perhaps selfishly) only concerned with what will put the best product on the floor for people who actually care about basketball, not people who will tune in to watch LeBron and Kobe regardless of what teams they play for.
If you care about "basketball" why would you not want an opportunity to see it at it's highest level? I think you mean you care about the Celtics.
But this is all an aside, because the current situation is nothing like the premier league where, as you rightly pointed out, the teams with the most money just snipe players. These recent player movements have absolutely nothing to do with capitalism and everything to do with wanting to enjoy your job and to succeed at it. The Big Tres in Miami all took paycuts. Chris Paul went to the Clippers who have a notoriously bad owner. DWill would be leaving a situation with a crazy billionaire who is willing to throw cash around.
These movements have nothing to do with money and everything to do with an empowered workforce wanting to do a job they love with people they enjoy with the goal of succeeding at the highest level, and I really can't fathom how that's a bad thing.
It's a bad thing for fans of teams not in big cities or warm weather locations.
It's a bad thing for team executives who try to make smart moves to build good teams only to see their plans fall apart because their players want to team up with their friends.
It's a bad thing for fans interested in watching a league with 10-15 good teams as opposed to a league with 4-5 talent-laden teams and 25-26 mediocre to terrible ones.
Memphis and OKC are both building young teams with great front offices-- Yes I did say that about Chris Wallace. In the past 2 years:
Memphis has resigned Rudy Gay, Marc Gasol and Zach Randolph
OKC resigned Kevin Durant, Russell Westbrook, Kendrick Perkins and likely will be able to resign James Harden and Serge Ibaka.
NBA players aren't leaving small city, non destination cities if the teams are good and the organization has direction. San Antonio is another prime example of this.
LeBron James left Cleveland a team where the second best player his team ever put around him was Anderson varejo.
Chris Bosh left a Toronto organization that tried to pair him in the frontcourt with Charlie V and Andrea Bargnani.
Dwight Howard looks to be leaving an Orlando organization that lacks the ability to assess talent.
Dwill left Utah in what was apparently a toxic and disfunctional setting.
Chris Paul got traded from NO when the second best player he ever played with was Tyson Chandler.
You can keep All Star and All NBA talent around if you have great management, don't blame the players if they go seeking that, like Bosh and James went seeking a great organization run by Pat freaking Riley.