Great quote from Tim Bray on the "View Source Lesson": "At this point, the RDF evangelists pipe up and say ?Well, Ordinary People (tm) don't have to look at the source, there will be tools to sort all that out.? Sorry, I just don't believe that. If, in 1994, you'd needed DreamWeaver or equivalent to write for the Web, there wouldn't be a Web today."
That last sentence succinctly expresses an intuition I've had but not been able to articulate. There's something critical about not relying on end-user tools to make a technology approachable. This is why I like XML-configured tools like Ant, and was suspicious of the early-day dreams of how Struts was going to make front-end development a drag-and-drop operation. Thankfully (for the fate of that framework) it is still quite usable without depending on the rapid development tools everyone was talking about on the lists in Y2K.
As Jon Udell paraphrases Dave Megginson: the formats that tend to succeed are those optimized more for humans than for machines.
Microsoft, on the other hand, has such a strong market position that they are able to put tools first; their developer community will simply wait for Redmond to introduce a new version with the latest feature. Macromedia was so far out in front with Flash that SWF gained a similar position, poisoning SVG. I still believe it is a mistake, though, for anyone without such a position to rely on applications to expose an accessible interface.