Greasemonkey is an integral part of the web experience for many experienced users. Google acknowledges that some people are going to change their own experience of our web applications regardless of what we do. Resistance, as they say, is futile. It would also be somewhat hypocritical. After all, a Google employee wrote Greasemonkey in the first place, another wrote these scripts to add functionality to Gmail, and a third wrote two books on the subject (and these docs).
