The controversy over Apple’s “photocast” extensions, and the strangeness of their iTunes RSS enhancements, is illustrative of the transition that software companies need to make as they become web-enabled. It’s no longer enough to make your applications and hardware pretty and functional, but the guts that other people get to see must look good too.

This is one reason that people prefer RELAX NG over XML Schema, for instance. Where markup is concerned, it turns out that the excuse “only computers will read it, and we’ll provide tools to generate it” doesn’t cut it. The web’s had a view-source mentality since it started, and the aesthetics of markup matter a great deal.

— Edd Dumbill (emphasis mine)