Any time you use your real name, real HR or potential employer sees what you did. I do not want my chance to find work be influenced by random HRs opinions on what google play games I rated or which youtube videos I have in playlist. Nothing really controversial there, but people tend to be judgmental about details.

Forcing me to use real name means that I suddenly must be super careful about everything and control everything the same way as I control work. Not worth it.

Yeah, and Google+ launched at around the same time this issue was already getting quite a lot of negative attention, including in the mainstream press and media as I recall.