I'm just curious as to why it's a bad idea? I click URLs in emails all the time. I just hover over it to make sure that the hyperlink matches the text. Is there another possible security issue that I'm missing?
Also issues with fonts having identical visuals for one and el and sometimes lower case eye, capital oh and zero, etc. And soon, probably (already?), unicode and other escape codes in urls.
DON'T RELY ON HOVERING OVER.
Besides, I was genuinely curious. I know about phishing, but I don't know if you had anything else in mind. I learn a lot from the HN community.
Even if (and that's a big if) the hover-over doesn't fake you out because of a bug, are you willing to make sure you don't suffer from any of the problems in this?