greenimi,
I once had 5-6 people saying that flatness controls coplanarity (on multiple planar features). I said it does not. I guess I was wrong because min. 5 people said otherwise. Maybe you also think whoever yells louder is right. Or maybe you were drunk when you were typing? You can use that as an excuse to save yourself.
So I will ignore greenimi and go back to the original sketch/drawing, maybe this time from a different view of angle:
Imagine you have the 3D model opened up in your CAD package. And all you see is a size dimension with tolerances (dia 15 ± 0.2), no basic dimensions at all. And you like to know the distance between the planar feature and the center of the cylinder. You use the measurement tool in your software and measure the distance from the planar face to the edge of the cylinder as 13.5 (in this scenario, it is more convenient). Then you would calculate 13.5 - 15/2 = 6. Would that be wrong? Why can't you do it in a 2D drawing? If there was no nominal value, then, of course, you wouldn't be able to do that.
All I am saying is that it is not the ideal way to dimension that feature from the edge of the cylinder. I would do it from the center. But in my opinion, it is not incorrect to dimension it from the edge.