I see a lot of guys that have the mpb thing shaving but I hardly see guys that have a full head of hair shaving it off. I have a full head of hair but I shave it because it just looks crappy if I let it grow. Ahh, such is life but if I let it grow, I feel so dirty.
I agree with @Razor X It takes less time to shave bald then to have hair. I also don't have to spend anything but razors. I use a leaf so no plastic bits. I use a bowl or plug the sink of water so more water saved. Me being bald is good for the environment and myself.