I don't think I'd want a penis... sounds like a lot of work and maintenance. Have to keep it clean, have to keep it safe from EVERYTHING including yourself (stupidity or absentmindedness), have to learn how to aim (who has time for that whey you really gotta go?), and then the damn thing's horny all the time ... and you have to either find relief in your own calloused hand or pray you can find favor in one of nature's most fickle creatures on Earth (women).
Nah.. I'm happy that a quick shower is good enough for cleaning, generally injury is not a major concern (except for freak accidents), sitting down is much easier to learn than aiming (and useful for emergencies), and except in very serious situations... horniness can be turned off or dissuaded rather easily, and when you are horny it's really not that hard to find a guy that's willing.
"The weakest soul, knowing its own weakness, and believing this truth that strength can only be developed by effort and practice, will, thus believing, at once begin to exert itself, and, adding effort to effort, patience to patience, and strength to strength, will never cease to develop, and will at last grow divinely strong."
- James Allen