Not a fucking chance. Nor would I date an obese person (spare me the "shallow" bit, please). In both cases you are disrespecting your body, and in my opinion, it is easier and more detrimental to disrespect your brain.
Through work, personal, and volunteer experience, I have come into contact with alot of Traumatic Brain Injury (TBI) patients. Abuse to the human brain is an undeniably terrible thing. Just weeks ago I was caring for a man with a concussion. It was 40 minutes before the ambulance arrived to take him away...in that time I WATCHED as his memory deteriorated...first he could not remember the day...then his mother's name...then his own birthdate.
A kid in high school suffered a TBI that completely disabled his senses of taste and smell forever. Imagine never tasting your favorite food again. Imagine not being able to smell a dangerous gas leak.
My best friend suffered a sub-arachnoid hemorrhage more than a year ago. For almost two months he was quiet and secluded and although he could identify a joke as "funny" he was unable to smile, or laugh, or feel excited.
I can't imagine how anybody could take part in activity that almost guarantees similar results. The injuries above were acute, one time blows. Imagine a lifetime of blows. Google up on nerve tissue - it isn't like skin or other epithelial tissues - it does not and can not regenerate. Knocking your brain against your skull is bad enough - the NCAA has strict guidelines on allowing multiple-concussion athletes to return. But the threat of meningeal tears and hemorrhages is ridiculous.
Call my compassion for the human brain "girly" if you want. There is calculated risk in every sport. I'm a gymnast and yes I've fallen and suffered concussions. But I'm not TRYING to...in fact I'm very careful NOT to. Boxers are trying to knock someone out, trying to bash a brain against a skull. And they do. And when they get that TKO, it means the brain they've been beating on has had way too much. And then they hit the floor, limp, and the brain takes another blow. The reason we react to falls with the parachuting reflex (a response to catch ourselves with extended arms) is to PRESERVE our brains. And make NO mistake, boxing fans, these athletes DO suffer brain injury and the effects ARE cumulative and durable.
In my opinion, the two least sexy things a man could do are 1-intentionally harm another person's brain and 2-offer up his brain for intentional harm. In the case of number 2, I generally assume that these brains must not be good for much else anyways.
Note - I have nothing but respect for fighter TRAINING. Hitting bags is great for your body and mind.