Agree, that fat xrayed outline is distractive as hell, and also disallow to read if objects are perfectly matching (for example, for checking model for 3d printing)
This outline constantly screams an alert in your face “Warning! Something is selected! Nothing else is important!”
It is painful even to think about working like that:
Where are my objects in 3d space? What and where do they intersect?
What is their best placement? Impossible to say. You are just focused on that thick screenspace outline instead of 3d objects, experiencing a severe overload of perception.
Keeping wireframe constantly on is not an option for complex scenes as well.
This outline is a serious perception breaking workflow issue.