According to browser stats some 1/3 of all browsers are IE6 that would not understand either <?xml version="1.0"?> prolog nor Content-Type: application/xhtml+xml header. What is worse, the first turns IE into quirk mode and the latter make it want to save document instead of rendering. It's a bit like pumping unleaded full up while having LPG fuel system.

In all Midgard templates and style element we promote XHTML tags but it appears that is somehow just a show-off that we are all aware of XHTML but actually we provide nothing special. Perhaps it would be valueable to look from distance and say that unless XHTML compliant browser covers at least 90% of market, it is pointless and perhaps maleficent to make 33% of browsers to misunderstand our pages. And please, think about poor designers that have to struggle with layouts :)