I was wondering what are the demerits of using XML over HTML or XHTML. I mean, both can be styled using CSS and scripted via JavaScript. Also idea of using XML over HTML sounds much powerful for the developer, since the developer has much much more control over his webpage. Also, without the pre-styled elements of HTML, the XML webpage would be much more cross-browser compatible.
Also, is there a reason that besides of XML being so much more advantageous over HTML, its not such a widespread practice?
PS: I'm a web designer and I have used HTML in all of my project so far for presentation of data. And unless I find a good reason for not doing so, I am thinking of using XML for my next project as I want more control over the data and its presentation.