Why HTML/JavaScript/CSS are not becoming compiled languages (or maybe even merge into a single compiled language)? What if browsers were running \"Browser Virtual Machine\" and
Your ideas have validity when they are applied to JavaScript. As others have noted, to one degree or another several vendors are trying to apply those principles to JS even now. Another big step in this area will likely be the Chrome OS Google has announced. However, when it comes to (X)HTML and CSS I think your ideas may be missing the point.
The world wide web is not a buggy and inconsistent application platform but a massive and unprecedented collection of interconnected documents. The power of the web is in the abstraction of the data from the often rigid (and breakable) visual layouts and increasingly complex in-page functionality largely provided via JavaScript. Encoding these pages in (X)HTML is ideal for making them accessible to the widest possible audience both in terms of browsers and in terms of technical knowledge required to author a page.
More and more the web is being used as an application platform - which is a powerful and exciting use of this technology - but we cannot lose sight of the fact that these Ajax-driven "web 2.0" apps are merely documents with extended functionality. Compilation doesn't make sense for a document and compression is already happening (via gzip and the like).
On a more practical note, the W3C moves at a glacier's pace and browser vendors take turns between jumping-the-gun supporting experimental features in unfinished specs and taking their sweet time supporting other specs which have been on the table and in common usage for years. The whole processes is like herding cats. I wouldn't hold my breath for them to make the kind of radical changes you're proposing any time soon.