I just tested the feature and I really like it
And I absolutely agree with the solution of coloring just a square instead of the full row.
But for one purpose I'd prefer to have the full row colored (the textcolor I mean). That's when I want to "grey out" specific tracks. When I want them to fade out a bit, so that they're out of focus, visually more in the background - do you know what I mean?
The way the dead links look like.
And believe me, I wouldn't dare to color the whole row in something like red or green! Because the tidy GUI was one of the primary reasons for me to switch to MB.