I started going bald late 20's/early 30's and just started cutting my hair really short and then never gave it another thought. Being bald isn't unattractive - being self-conscious about being bald is.
I personally agree that it's not unattractive and being self-conscious about it can make it so. However seldomly people with a perfect hairline worry about that, and many balding people do so it's at least another thing to get the upper hand on. And it's also no suprise a lot of people fear it.
Published data indicates that when women rate pictures of balding vs non-balding men, the former are rated worse and one could say the attitude one has would not have much of an impact on that.
And it's the same with height, perceived fitness and wealth.
What I am trying to say: It's simply not a level playing field and all these things add up.
Being bald works well if you have a big frame/size. Then you just look very masculine. Unfortunately short guys are more likely to go bald and it works less well on short men.