SU 2017 Poorer Line Quality

No, you are not alone:

I find quite annoying that the lines will appear thicker than 2016 on high DPI screens (such as your WQHD) When the model has a lot of lines, the model is more susceptible to look just black blob.

and the anti-alias settings may improve, it doesn’t make it appear as thin as 2016.
I feel you @Guy (I know the pains of MAC is worse than windows. I moved on…)