Quite honestly, they do a flipping good job of what they're intended for - i.e. a big, bright, illuminated version of a marshal's flag.
Now whether they should be modified to provide further information to drivers, or for the way they present that information to be changed, I'm not sure.
Short of having a light on your own dashboard that is triggered by proximity to these lightboxes, and shows the same information (which would be cool, but technically challenging), I'm not sure they can be improved.
Having said that, the usual problem with flags at marshals' posts is that when you're following a car pretty closely, you can't always see them. With the safety requirements, sometimes marshals' posts are off to the side of the sight line for drivers when braking or turning in, etc. The lightboxes suffer the same problem to some extent, as they're usually based near marshals' posts, albeit usually mounted a bit higher up.
If they could be mounted a bit closer to where the driver is looking at any given time, then that would be great - within the reasonable limits of safety - i.e. if someone goes off on a corner, you wouldn't want to be smashing into one of these things.
Failing that, as I say, a light on the driver's own dashboard would be a great solution