The reason you do see too many M Sports on the road is because-
"WE ARE ALL STILL WAITING FOR OURS TO ARRIVE".
Sorry, moment of frustration there.
One of the reasons is that the M sport takes slightly longer to go through production, and usually is more optioned up, so the output numbers are lower.
The main reason, is price, as you can see by reading many of the comments from new buyers on this forum, saying that their main want was to get into a 1er. Unfortunately BMW is steep on prices for options and this also limits the sales of M Sports.
I am more than happy not to see tooooo many on the road, or is that just being a bit M Sportist.