New theme?

Alright so, I reached home today late in the evening, from a long, long day of school (f*cking hate filing).
Then my cute little brother greeted me "Hello, "Grey""(not, duh...) and my mom wasn't very happy with it. She began a gentle lecture with him, teaching him to greet me as big brother (to display respect), which then sparked a dilemna within me (even though it is none of my business)...
Okay, so, I was wondering, why is it considered 'rude' to refer to an elder in the family with his or her name/full name.
What I can think of is:
1. It is rude because it is considered rude by alot of people.
2. It is rude because it is a tradition.
3. It is rude because you should not refer to an elder with his or her name.

What made me doubt this seemingly illogical tradition:
1. It is illogical. (To me, at least)
2. It does not make sense.
3. AT ALL.

I admit that I too agree by heart that it is rude but my my logical side says "NO. Scr*w that r*tarded tradition - it makes no f*cking sense!" I do not dare refer to my parents with their full names; or my grandparents; or my relatives.

So, what do you think of this tradition? Leave your comments in the tagboard.