I don't think greasemonkey is as easy for my grandmother as a plugin - yeah I know my grandmother might not care about seeing the long url (or know what one is) but the premise is the same FF plugins are easier than greasemonkey... for the average user
You have to restart Firefox to install / enable / disable extensions -- with Greasemonkey you only have to do that once. You also don't have to deal with addons.mozilla.org and their wanky policies.
http://www.longurlplease.com/
Still, I think you're on to something; Greasemonkey might be the best of all worlds.