I haven't heard about any other superstars wanting to play in Miami. Nene, if I remember correctly, is the best player to have been linked to Miami and they were one of three teams he's interested in. Other role player type players flocking to Miami isn't a problem.
But regarding stars, why is it so surprising that they are interested in playing in LA or NYC? LA is coming off b2b titles while NY is quietly on the upswing while building a good young core. Players want to win and those teams put players in a very, very good position to do just that.
With CP3, his team isn't a contender and the only assets they have are David West (who is the 2nd best player on the team) and Marcus Thornton (who can't get consistent mins to even increase his value). They did have assets in Peja's expiring and Bayless but what did they do? Bring in CP3's "friend," who happens to play the same position as CP3, and a bunch of crap. Instead of making an upgrade and going for contention by targeting Iggy, for example, they go for.....crap. Is it so surprising that he wants to go elsewhere when the teams owner (well, former owner) wouldn't commit to building a contender?
With Dwight, his team was a contender yet they felt the need to overhaul it now. That got them a bunch of expensive, aging role players in return and the team doesn't seem to be much better. He's basically in the same position as LeBron was in. He's surrounded by role players, many of which are older, and the team has little to no flexibility to make future significant improvements. I give ORL credit for trying to make strides to get better...but they just weren't able to bring in a significant upgrade and they won't be able to in the future. Is it so surprising that Dwight is considering walking away from that if they don't win a title?
And then if they want to leave, where would it be "OK" to go? Small market teams, excluding OKC, typically don't have tons of cap space. Minnesota has/had a decent bit, but that organization isn't run well at all so I could see why stars would shy away from there. Sacramento has some young players and cap space....but with the likelihood of them moving the star wouldn't even know where he'd be playing in a few years.
Again, I think CP3 and Dwight leaning towards leaving is totally understandable. But as far as where to go...which teams have the space to get it done and are actually appealing? Not many, for various reasons (such as the front office or future location, as noted above). NY just happens to have a lot of cap space and young talent coming up and LA has a good young center (tho he has injury probs) to offer via trade. It's the "perfect storm" so to speak: the team is good, has a committed front office, can actually acquire a star, and happens to be in an appealing city.