Rewinding a bit from computers doing all the writing, are you using any tools that help you write considerably better (not just spelling/punctuation checking)? As a non-native English speaker I would like to have a tool that points out my nonstandard usages of language. I think it could be something as simple as parsing the text and searching it against a corpus, but I have no idea how many "unique structures" a text…
prowritingaid has a very good, free, web-based tool that will parse out all sorts of neat things in your work. for example: i write fiction and have a real problem with “echos” — words that i repeat within a certain distance of each other — and i even miss them when proofing/editing. pwa is a godsend for this. if scrivener would add their own native version of this (hint hint incase any of you L&L people lurk here..…
Actually, I find that constant repetition of the same words is absolutely necessary in technical writing. I used to do this thing where I'd try to write my research papers as if I was writing literature, trying to find new ways to say the same thing to avoid repetition, and I got some really harsh criticism as a result. I went to my university's center for academic English and they pointed out my mistake to me and suddendly it was blindingly obvious. In a technical paper you have to use the same exact words to refer to the same concept, or you will immediately confuse the reader, who will think you mean two (or more!) different things, one for each different turn of phrase. So I adjusted my writing to exploit the rythm created by the repetition of the same few words every few sentences, because of course I want to convey a precise meaning but I also want my papers to read well. And now reviewers note my papers are well written and clear; and so far nobody has complained about repetition.