Ghost, you are trying to make it a black and white issue when it simply isn't one.
Yes, you can change the transmission fluid. That action may precipitate a transmission problem, even if you didn't have any symptoms or problems before changing the fluid. That isn't BS, it is just fact. And it isn't limited to BMW in any way.
At the samed time, changing the fluid doesn't guarantee you will have a problem afterwards. So posting that you changed it and didn't have a problem isn't at all a surprise. Statistically, a sample of one is meaningless.
What is important to judge is the benefit of changing it vs the risk and cost of doing so. Some believe that that equation comes out positive, others believe it comes out negative. BMW has changed their recommendation in both directions at times, but for new transmissions. They didn't go back and change their previous recommendations for transmission that were already out there.
I could post a long complicated answer with data sheets if you like, but I just did a search and I see that I have personally posted 126 times on the subject of transmission fluid on this board, dating back to 2006. Not sure why I didn't post on it in 2005, but the search doesn't lie. So have a look at those posts if you like.
Just a side note, but that manual also says you must use only BMW OE parts. Ever used aftermarket sparkplugs, brake pads, and so on? Don't trust everything you read. Boom.
