Shyness - In offline life, here shyness doesn't come into picture at all. Afraid to show identity - nope Not interested in showing my identity - yes, because I hate attention. Even tiniest attention.
Now main reason, Because I want to go anonymous. If I don't use anonymous option then anonymous radio button will stop working or it may start malfunctioning. You know, you've to keep using things in order to keep them in their best condition.
I think it's a combination of all three. It just depends on the person. I have seen users say they go anonymous because they simply want to post opinions without making friendships or connection. Others are very private with their information and what they post online.
Improve your English please. All kinds of reasons are possible. Maybe they just want to hide the fact that they are on this site - from parents, friends. They are embarrassed with identifying themselves when posting certain things - don't want to be made fun of. Personally I never post anything that might hurt me later on. So I got no reason to go anonymous.
Once in a blue moon... because i stand by what i say. some askers just have deep stuff and its embarrassing... the ones that posts opinion either don't want to be judged by their view... or are just trolling.