I suspect common reasons for taking on a low-level management role include a) developer burn-out, time to move up and not have to code all the time; b) desire for more power (whether for egotistical reasons or in the hope of effecting positive change in a position of power); and c) a stepping stone to further levels of management where the salary upgrade actually becomes tangible.

I don't disdain competent developers who move up, I just personally don't understand it - yet. I imagine the time will come where I've had my fill of programming. Even if I don't burn out, I expect I will reach that age where I begin to feel that younger developers and management are dismissive of my abilities, and it will be the only escape into a role where I can earn back some respect. :)