> Unneeded use of separating lines, grouping boxes,.. less of these = easier on the eye.
I seriously disagree with this particular assertion. I find that "flat" design trends make things much less usable, and this is no exception. It is far easier to group things with visual references than with lack-of-visual-references. And it is far easier to find things like buttons if there are, say, actual indications that they are buttons.
There's a balance to be struck. The pendulum may have swung too far towards the minimalist, but it used to be much more common to have lines and boxes around everything, where simply removing them and leaving open space made the layout easier to quickly grasp.
I seriously disagree with this particular assertion. I find that "flat" design trends make things much less usable, and this is no exception. It is far easier to group things with visual references than with lack-of-visual-references. And it is far easier to find things like buttons if there are, say, actual indications that they are buttons.