When you scale an area lamp, it’s data don’t follow it’s physical size in a viewport.
That is one problem that needs to be fixed. Now it is possible, that you have very big area lamp in a viewport but in the lamp settings, it actually is very small.
It took me quite while to understand that I should not scale the lamps ever in a viewport because it leads to misleading information. Now If you apply the wrong size in the viewport you have no any visual way to know what is the real size of the lamp.
If those two data values can’t be connected, then the scaling should be disabled at all in the viewport.
Maybe other lamp types should also have some kind of indicator to show their physical size in the viewport?