Now, more than ever, it doesn't make sense as to why Orochimaru went to so much trouble to switch bodies when he apparently already knew how to attain the ultimate state. Immortal, regenerating, unlimited chakra, and you can even use it on yourself so you aren't under anyone's control.
I assume that you keep regenerating to your previous form, so you can never really improve. You'd want to be "resurrected" at your strongest state. Plus, there's also the problem that you have to die first, which is... risky.