Did good morning stem from people stating the fact that “this is a good morning”?

I believe it is a 'command.' (Have a) good morning.

I believe that methos5000 is right. Your question reminded me of this part of The Hobbit by JRR Tolkien.

"What do you mean? Do you wish me a good morning, or mean that it is a good morning whether I want it or not; or that you feel good on this morning; or that it is a morning to be good on?" -Gandalf

I also like this quote from George Carlin.

There is a problem with the term, "Have a nice day." It puts all the pressure on you. Now you have to go out and somehow arrange to have a positive experience. All because of some loose-lipped clerk. Have a nice day, indeed! Maybe I don't like feel like having a nice day. Maybe - just maybe - I've had 27 nice days in a row, and I'm ready for a crappy day. You never hear that, do you?

"Have a crappy day?"

"Why, thank you. Right back at ya!"

A crappy day, that would be easy. No trouble at all. No planning involved. Just get out of bed and start moving around.

Some people always seem to be "great." Not me. I don't give them any superlatives; nothing to gossip around. I tell them I'm "fairly decent." Or "relatively okay." I might just say, "I'm moderately neato." And if I'm in a particularly jaunty mood, I'll tell them, "I'm not unwell, thank you."

Thanks, methos. I should've thought of that.

That "have a nice day" thing is so true.

I'm moderately neato. That's funny.

Thanks.

'Good morning' is an oxymoron anyway.

So....What do you say?
Hey! Hi! Grrr!
"How are you?" is the worst!
I'm not interested in how they are, and I don't want to tell them how I am. I want to acknowledge the other person as a member of the human race like me. Even animals have a "greeting" ritual. So... What is better?