I'm frequently aghast at how utterly _terrible_ most technical documentation is. Even the docs for a lot of prominent enterprise and open source software is just awful to use. What drives me the most insane is dry, passive voice. Passages that descriptive rather than prescriptive ("the widget is a surmounted on a logarithmic casing, widdershins of the two spurving gears"), contain zero diagrams or illustrations of how things are put together, and _definitely_ don't contain anything like a tutorial or getting-started guide.
Every once in a while I consider jumping into the field of technical writing just to clean it up a little. But I would probably find it immensely dull after a short period of time.