I recall back on the old Roadfly forums that a BMW transmission engineer actually did post in a thread about this same topic. Anybody else remember that? I went back later and tried to find that post but never could.

Anyway, from what I recall he had very clear reasons for why he (and therefore BMW) did not recommend fluid changes. I can't recall the specifics, but I think it was similar to what JCL said. Basically that they weren't necessary and that changes carried an element of risk. That post influenced me sufficiently that I never bothered to change the fluid on either of my BMWs.

Just to throw out my own anecdotal evidence, those BMWs are/were: 2002 X5 with 110k miles - just traded it in last month. And a 2002 330i with 110k miles still on the original fluid. I hope to keep the 330i a couple more years, so my fingers are crossed.