Are they max contract players? I thought they each took a pay cut to play together?
Their contracts are all like 90% of a max contract, it's close enough not to matter a ton in trades. They also got a deal where in just two years they can all be free agents again which is not very standard.
Effectively you could trade any of the three of them for any other player in the league no matter how good that player is and still get around cap situations.
If I'm GM, I take LeBron-Wade over any other combo in the league, but adding another max or basically max contract instead of a real team doesn't make sense. It makes sense from a "let's play superfriends" point of view but not basketball. They may well win a few titles, but I think it would be easier with just LeBron-Wade and flexibility to build a better team.