Screens got larger and higher resolution, and UX engineers decided we should fill the extra real estate with white space because...reasons? Because they're trying to appeal to the lowest common denominator that finds more than 3 elements on their screen confusing?
Bring back skeuomorphic design. Make buttons look like buttons again.
Look at how much you can fit onto a 1920x1080 display running Windows 2000 compared with a recent release of GNOME.