Personally, I just want to properly handle this edge case and it would bother me if my sites didn't handle it correctly. There are advantages for using FQDNs since they are not ambiguous there are extra optimizations that can be done. I don't want my sites to be problematic for people who want to use them so I make sure my sites properly handle them. Usually handling FQDNs is easy as it just works out if the box on most server software.
