To be totally honest with you, I never paid any attention to the side mirrors, but now that you mentioned it. I would prefer them to be attached where the mirror are normally, instead of on the door itself.

It was explained to me that the side view mirrors were moved down to the doors because it is 'suppose' to be a coupe (I still think labeling the car a "4-door coupe" is a very lame moniker). I wish the auto industry would just drop that phrase altogether.

I noticed the Audi A7 has them on the doors too.

All I know is, the location of the side view mirrors on the previous model (C219) presented a lot of difficulty when turning.
There were times when I couldn't see the island or the curb as I was making a turn because the mirrors were right at the level where it would obstruct the driver's view if looking down at the curb while making a turn. Especially when turning to the left. My car was a left-side driver.
I'd imagine those in Europe with the right-side driver have difficulty spotting the curb when making a right turn.

The C218 no longer has this issue...but why did they need to make it so damn tall?!!

Mercedes Benz

Despite that fact, I still love the look of this car.

Oh, no doubt.
Please don't get me wrong...this is THE sexiest car MB has built with four doors.

the true reason behaind the side mirrors is that so the car will be more quiet when driving it.

I never noticed wind noise on the previous (C219) model and that one looks gorgeous on the car.