Yesterday I had a brief chat conversation with my friend Livio where, among other things, Livio pointed out that the HTML5 specifications are too complex when compared with the XHTML specifications. In fact, XHTML specifications fit in a dozen of printed pages, whereas the HTML5 specifications require at least 900 pages. In the last ten years there have been other cases of complex web standards, such as MathML and SVG, but HTML5 makes a case on its own. The problem with complexity and web standards lies in the fact that a web standard must be adopted by people who make web sites. Success or failure depend on the number of web developers who actively use a standard. In that vein, SVG and MathML were a total failure, because the average use of these standards is pretty insignificant. But why so? Because they're too complex. In SVG, if you want to build up a site logo, you have to write several lines of code. That's completely different from rectangles, triangles and circles presented as examples by the SVG specs.
Adobe, promoting SVG since 2000, decided to include some features in its applications to export graphics as SVG files. That is what most developers do, obviously without knowing all the nuts and bolts of more than 800 pages of specifications. Who can actually blame them? A golden rule in usability is to find the simplest solution to use something. And this is a simple and easy solution.
HTML5 seems too complex to get you started using it at 100%. If we conduct a survey among web developers asking them how many features of HTML5 they actually know, we will probably be surprised by finding out that, beside headers, footers and navs, the most relevant thing is the DOCTYPE, because it's the simplest thing to remember.
Take for example the new media features. The goal was to simplify the market of vendor formats by introducing a common format to share audio and video files. Result? To the already existing plethora of more than 12 available formats two new formats were added, thus resulting in a total of more than 15 available formats. Now browsers have to choose between OGV and MP3 for audio files, increasing the level of complexity and the confusion from web developers who don't actually know which format to use when they want to insert an audio file on their documents.
I'm afraid that history will repeat itself as in the case of SVG, thus dooming HTML5. I hope I'm wrong.