Why does everyone look to get a ton more edcuation (and edcuational debt) than you need to perform the job you want? That said, sure a Phd won't hurt, but will it help? Depends on the hosptial, situation, etc. It would probably help more to have a MD/DO/DPM/DDS/Phd, etc. attached to one's name --ALL AT THE SAME TIME -- but is this REALLY needed? Of course not.
There's a limit to what you will do in practice and thus having a bunch of credentials unrelated to your chosen craft, will eventually lead to diminshing returns after awhile. Don't mean to sound flippant but I don't think it matters much, unless your into research and not patient care.