When I upgrade to 4K it will be to show more content on the screen, not showing the same stuff with more pixels. Scaling is irrelevant.
My current setup is a QVGA 27" primary flanked by 2x 23" 1920x1080 monitors. The pixel densities are close enough that dragging windows between displays doesn't jar badly and it feels acceptably close to a single wide surface (albeit not rectangular). Again scaling is not just irrelevant, it would be bad.
Even my phones offer differing size icon grids for each screen size.
In any sane implementation any scalable elements would be rendered scaled then cached, no need at all to make the initial render efficient. Scaling is a BS excuse for this crap.
These are just piss poor graphics. If they insist on rendering them with vectors then they need to spend more time getting them right, instead of blaming