I guess it all comes down to BMW. Why remove such a useful technology that has been helping mechanics, racing teams, and vehicle owners for as long as I can remember. Way to go BMW! As far as I am concerned, the dipstick did not bother performance at all. Then why remove it? When BMW removed the dipstick, it created speculations and doubts (like this thread) on how to check the oil level and it's cleanliness. To make matters worse, a lot of BMW owners are losing trust on their dealerships because of this dipstick issue.
Someone correct me if I am wrong, but high performance cars such as Porsche and Lotus still use the dipstick to this very day! I just don't get the point on why BMW decided one day to take the dipstick out of the engine...