Canonical URLs shouldn’t be default – it breaks too many things

The new canonical URL “feature” sure does break
a LOT of things. It breaks any site which uses
cookies, for example, since cookies for http://www.site.com
won’t be sent back to site.com. It breaks PHP
sessions for the same reason. It breaks stadard
basic authentication, as a browser which has saved
the password for http://www.site.com won’t send it to
site.com or vice versa. I could go on, but I think
you get the point. In my opinion this should definitely
not be the default setting. Generally, anyone who comes
to us with WordPress problems, 80% of the time
the problem traces back to this canonical URL
misfeature. As an optional feature or plugin, fine,
but the default setting shouldn’t be one that breaks
so many things on so many sites in ways that are hard
for the typical webmaster to diagnose.