This reminds me of DOCTYPE switching. From http://hsivonen.iki.fi/almost-precedent/: "Back when the Quirks Mode and the Almost Standards Mode were introduced ... committees created specs and that were enshrined as W3C Recommendations before there was solid implementation experience. Then the Web Standards Project lobbied browser-makers to implement the W3C specs as they were. The mindset was that the specs given from above couldn’t and shouldn’t change. People thought that vigorous upgrade evangelism would work and make Web authors change their existing sites."
Note that the Web Standards Project was also the one petitioning Netscape to cancel Mariner, which ended up contributing to the problem. Why did non-IE browsers have to implement document.all?
1. Unlike print layout, the dimensions of a webpage can change, and so we slowly invented an evolving layout framework for something without fixed dimensions. I've done typesetting since it was exacto knives and hot wax, and if you told me then to imagine a stretchable paper for news I would have cried in the corner.
2. The layout framework was independently built by a bunch of separate companies, who by nature of competition weren't going to agree on everything (see every browser).
3. The agreements that WERE made were done by committee, including the reluctant inputs of competing companies. This method of design will guarantee that they end up with something weird.
4. Make it backwards compatible with all the previous ghosts of architects past.
Imagine if Ford, GM and Chrysler had to build a joint car every few years.
Also, try designing a page in Flash and using (or just reading about) their graphics/layout/text frameworks. Some things are much harder than HTML/CSS, some are much easier, but it offers a great comparison on a completely different way of solving layout. I've implemented a spec like CSS for customizing Flash app appearances, and compared to what existed before, it made everything better.