First of all, it's not something that really ever gets verbalized, in my experience. When I shaved a full (almost) head of hair at the age of 31, back in 1995, I was partnered, at the time, to al older, balding person. We never discussed it, but after I shaved mine, he shaved his. I do recall getting lots of attention, being tall, broad, decent looking with a threatening shaved head and dark beard (guys of all ages). As I got older, and I was single, I was dating guys who were bald, shaved and had hair.
Jump to now, as an older guy, I tend to attract younger guys, who love the balding/shaved big-bearded look.
So the answer is, it crosses all generations. The younger, balding gay guys run the gamut from doing nothing (but buzzing short) to shaving. I only met one guy with a hair system (age 24). Older guys, same thing. I need to add that I tend to date within a circle of men who are basically NOT your pretty boy, skinny, club going type of guy. I tend to date in the leather, biker, bear (Google it) communities which tend to NOT put a huge emphasis on head hair. They DO tend to put an emphasis on body hair and facial hair.
This was true of the US, Israel, and a number of places in Europe.
Ha, more than you ever wanted to know!
I am glad to be on this forum, some really cool people.