I said no, but quite frankly I don't really care.
I obviously chose to put my first name as my screen name. On other forums, I generally put one of my parrots' name. They also generally have the field of the first name optional and I generally don't fill it up if I used another name as my screen name, unless I've been an active member of the forum for a while and everyone knows my name anyways.
If it does go up, I wouldn't make it mandatory. Some people might just not want to put anything, initials included (plus I feel it's rather silly to have a field you have to fill up but where you can put whatever you want..)