Ronnie,
I think you'll find, although not being in the US I can't be 100% certain, that it is the HIV situation that prompts this question on the form you fill in.
The first cases of AIDS were diagnosed around 1981, if my memory serves me right. Allowing for several years between infection with the HIV virus and the development of AIDS symptoms, this will explain why the question refers to 1977.
Certainly here in the Republic of Ireland there is a similar question asked, and if you answer 'yes' to it you will be told that you are not permitted to be a blood donor.
Obviously the reasoning is flawed, since the rate of HIV infection per head of population is nowadays greater in the heterosexual population and the intraveinous drug using population.
I understand that the USI (Union of Students in Ireland) is currently planning a campaign against this discrimination.
The Blood Donation Service here in Ireland regularly runs radio and TV ads, asking people to sign up as blood donors. "Join The Most Extraordinary Club" - or something similar - is the slogan they use. As you say, if there is a shortage of blood products, it is either ignorance, fear, or just bloody-minded discrimination that they still don't allow those people who admit to having male to male sex to become members of the club.
Marty