Simplification. I know what my scroll bar looks like and prefer it not to have multiple borders and shadows. It's easier on my eyes and mind.
(I don't love everything about "flat design", but not everything needs to be super skeumorphic)
(I don't love everything about "flat design", but not everything needs to be super skeumorphic)
Windows 10 does BTW not allow to change the scrollbar colours even though it was possible in most older Windows versions. They simply don't care about accessability and userability these days.
Ideally we could all choose our preferred themes like we can with GTK.