BMW will test with certain oils and make their recommendation based on that. They can't/won't/don't want/ test with everything out there. I'm not saying that everyone should run out and use whatever, but I do agree with Radiation Joe.
Regarding the whole rod bearing thing and BMW switching to 10w60, that was partially because they didn't know WTF was causing them to go boom. Prior to that M3's with S54 engines were recommened Mobile 1. It took BMW a while to admit there was a problem on their end and come up with a solution. I think the 10w60 switchover was just some added insurance -- or they got in a pissing match with Mobile 1 over prices.