What is XML, and Why Should You Care?--McIlroy

Why Isn't XML Everywhere?
So if XML has all of these powerful features, why is it not already in use everywhere? There are several reasons.

First of all, it's very new. The full specifications for the format are still under review (although a partial specification is now available). With the specifications still in flux, the available software tools are few, far-between and pricey. Mainstream software like PageMaker and QuarkXPress has little or no XML support. XML remains complicated, and we've seen again and again that the market moves slowly when technology gets complex.