-Slightly easier to write
-Very lenient on coding errors (HTML parser will correctly close unclosed tags, etc).
If you have Tidy plugged into FF, any errors are instantly apparent when checking on your local server, prior to uploading to the web server.
-Compatible with all browsers.
More specifically it's compatible with IE, which still has the lion's share of users, whether we like it or not.
-Significantly more strict on coding errors (This is an advantage for some people like me, makes fixing problems much easier if code is valid).
Irrelevant if you are using something like Tidy, and corecting HTML errors as flagged up.
-Faster parse time (if served as XML to supporting browsers).
-It's XML. It means you can define custom tags, much more document control, etc. (again, only if served as XML to supporting browsers).
True - for supporting browsers. But for the majority who use IE, not true.
You think HTML isn't as 'future safe'? HTML5 is on the horizon.
Frustrating though it is, without IE support, xhtml potential will not be realised on the web. As I read it, IE8 will probably not support xhtml. Maybe IE9 will. In the meantime, this advice remains sound, I think.