We're all humans and do things differently based on our understanding and training. A G'day and Thank you isn't the end of the world, but all of you who agree with saying it should admit that you are breaking the rules.
Just fess up and say that you are breaking the rules on purpose (but... add your excuse here).
My excuse is I usually respond in kind to a pilot who intitiates a greeting, (if i'm not busy) but don't usually initiate it myself.
It's the rule breaking principle. Don't break or bend rules on purpose. You break enough of them without trying or knowing it, and if you break a rule, and make a mistake at the same time, the cheese holes start to line up.
And as an acknowledgement of good work, a call to the ATC works great every once in a while.
Mike