This way if somebody gets lost wandering around, they can quickly find their way to where they started without trying to retrace their steps. Banner and navigation art can be unrecognizable. Even worse scenarios are possible with background images, or background images with print on top. Even if everyone were to use the same browser, not everyone would have the same resolution as you. It really never was intended to be as specific as a word processor, and its fundamental structure reflects this.
Nobody owns the web.
Therefore, standards are rather difficult to enforce. Venue first looks at what is the minimum you can use and still have a great looking site. Venue will use very basic color schemes and avoid noisy background images. Not doing this prevents a lot of people from enjoying your site. Remember most people are using either 28.8K or 56K modems.