It displays full name in stream and comments..
but
displays user name in chat box, blog post,videos,notifications,

Then why there is full name in stream and comments

the full name is there on request of the users here. They wanted streams and comments like FB.

But it should be better that there was option for the users that they can hide their real name.

If you writhe your username in realname, you have fix it.

Ok this for me.. not for users..??

I can se if i can fix it from 3.3 :)

We will fix it soon. Thanks for the reporting.

any news

i think this thing even not fixed in 4.2