I agree that having other elite defensive players helps you play better defense yourself. When you don't have to focus on covering for other players' lapses you can focus more on your own man, that's just logic. Having more defensive minded players on the roster would certainly help guys like STAT who've never been known to be strong defensively, no doubt about it.
But the problem lies in the coach's philosophical approach to the game, because of his high emphasis on playing uptempo and high octane scoring, the types of players that Donnie Walsh targets is sorta limited. His rotations are also often determined by the players that can hit open jumpers and bring something offensively to the table. Yes, it's true he's playing Ronny Turiaf and has played guys like Jared Jeffries in the past, but that was out of absolute necessity. No coach is going to only play offensive minded players, but in general their rotations are directly influenced by the type of system they want to run. Ben Wallace became a defensive star player in Detroit playing for Larry Brown because he had a defensive approach, a defensive philosophy to the system he was trying to run. Wallace would never have had that same opportunity if he'd stayed in Orlando because the system they were running was more offensively oriented.