Not all of those identifying bits have anything to do with the web. For example, your OS, your monitor size and color depth, the fonts you have installed. Those things make your overall computing experience useful, whether or not they improve your web experience.

It might be more practical to work towards browsers that do not have access to data that is not relevant to the web experience. I do need to know the size of your browser window. I do not need to know anything more about your video capabilities. In an ideal world, I wouldn't even need to know your browser, I would just need to know its capabilities. Your browser needs to know which fonts it can display, but my web server doesn't need to know that.