I agree with you, and it's really the most logical swap out there (and practically the only one to be made due to Phoenix's lack of salaries in Rozier's range). Boston would be glad to send back their late first, I suspect, just to lighten the draft pick load.
Phoenix loses shooting in Bridges, but they replace it with Rozier's shooting, and since T-Ro would no longer be trying to play his way off his team, he'd likely improve quickly. He'd also be a culture upgrade given that he spent his incubation period on a real playoff team.
EDIT: Bridges also shows promise as a 3&D starter, which opens up so many possible avenues for Boston. Cashing in Brown for a couple of lottery picks would help turn that Brooklyn deal into the Celtics' version of the Barry Pederson trade (the trade gift that just keeps on giving, even a generation later).