> I've been looking for a good book that really details the underlying mechanics of aikido (rather than techniques or spiritual waffle).
I couldn't find one, so I wrote a couple. (See the book reviews in AikiWeb, or check out http://hometown.aol.com/spitzpublishing/
> Why aren't these types of books out there;
Because they are hard to write.
> Sometimes I wish sports scientists would grab a group of Shihan, stick them in a room and force them to write a book about the mechanics and psychology of aikido.
Me too. I'm just a rocket scientist and not yet a shihan.
> Are these things too difficult to put down on paper?
The mechanics are not too difficult, though to do it right you need good instrumentation. The psych is more difficult because it is hard to measure.