As a healthy gay man I see no reason whatsoever why I can’t donate my blood, other than ignorance and blatant discrimination.
To the people who have long supported this ban and think the resulting donations are from the best possible pool of donors, consider this: not only are promiscuous straight men donating, but also gay men and bisexuals who aren’t honest (sometimes closeted, sometimes not). The reason the blood supply is relatively safe is simply because the blood itself is screened for HIV and other diseases.
Since I generally follow the rules, my blood is worthless to the Red Cross because I refuse to lie about my sexuality. Since I’m 52, that’s a lot of lives that could have been saved. Who shall we blame for that?