Here is a great presentation by quirksmode about the gaps that lie between Web Developers and Application Developers. Page 3 and Page 4 of presentation:
Web Developers
* Excellent knowledge of HTML and CSS
* Excellent knowledge of accessibility
but…
* No knowledge of application design
* spaghetti coding
Application Developers
* Excellent knowledge of application design
* Structured coding
but…
* No accessibility knowledge
* Little HTML and CSS knowledge
On a funny side, I am really confused: I am working as a (Desktop) Application Developer, and I thought when I start use the AppsBuilder, I will automatically become a Web Developer. It turns out I won’t, until I learn HTML, Javascript and CSS. I don’t want to, I don’t want to, I dont’ want to! I don’t want to fight with every browser weirdness on earth. And that’s untill I need some cool effects. 
Update
As I read my post, I’ve wrote it quite confusing, so I will update it know.
Of course I think XHTML, JavaScript and CSS are important. They are “the bolts and nuts” of web application development, and every web developer should have a good understanding of them.
My problem, and I think most of the people coming from the Application Development world, starts, and with most f them ends, with browser incompatibilities. When you have to fight over and over on some weired problem, doing a thousand google searches, so finally you find a hack so every decent browser on earth can understand your code. That’s the problem, and that’s why I don’t want to deal with “low level” languages.
Not that I am not keen with JavaScript, I found my self an intermediate JavaScript developer.
So that’s what I’ve meant with my blog post (I don’t want to, I
don’t want to, I dont’ want to! ).
I really hope AppsBuilder will help a lot with this particular problem.