I do not think it is laziness in all cases. I personally choose the option that is best suited for the circumstances.
But if you really feel that people are being lazy and picking the biggest button, why not re-label the "reply" button to read;
"Please consider the extra data usage and click this button to reply without quoting any text or pictures"
Then it will be much bigger than the "reply with quote" button and all the lazy people will pick that one. :2tsup:
Cheers
Doug