Earlier quoted context omitted.
That's modern medical 'ethics' for you: damn the consequences, what matters is what it looks like and whether it offends anyone.
No, it's about the safety of the blood supply. It's a weird quirk of human psychology and economics that paying for donations means fewer healthy people and more people with infectious diseases donate when it's fee-for-blood.
And of course thousands of haemophiliacs in the 80s got infected with HIV and HepC because of contaminated Factor VIII: http://en.wikipedia.org/wiki/Contaminated_haemophilia_blood_...
[0] http://www.onereads.org/spillover-david-quammen?page=0,208
[1] http://lambsbloodblog.wordpress.com/2013/01/11/hemo-caribbea...