Make use of the second monitor that many people already have anyway.

Svardskampe

Supreme Commander style, you get an overview of the map on your secondary screen. This could be very helpful in this game as well for the ones who use more monitors. Ones who don't can keep the map overlay with C.

AurOn2

The reasoning behind this not ever happening is: Not everyone has a second monitor and nobody want's to give anyone a competitive advantage......
Which is silly, really. the fact you have to look in a different direction to see a map, it's actually more efficient to press c (or whatever your map key is, q in my case) ESPECIALLY IF You have a clear maps mod installed.

NedStar

I use it in supcom and would welcome it in NS2 but I too see it having little benefit if its just a "map". Add some tactical information like all the players followed by their health/ammo and we'd be getting somewhere as this would provide extra information that you wouldn't otherwise be able to cram onto your screen without severely obstructing your ability to command. Cram in a first person view of a selected player and I'd be loving it.

I already have the big map open as comm for 90% of the time with the translucent map mod.
I find this giving me the best insight of the map versus the crappy small minimap.
As an actual player on the ground I would never glance to another monitor to see the map, it makes you much more vulnerable then looking at the map on the same screen.

Looking on another monitor didn't really do it for me in supcom either. Sure I glanced to on it on occasion but I usually just found myself zooming in and out on the main monitor.
Best purpose I found for dual monitor on supcom was to zoom into one of my bases so that I'd catch any movement from my peripheral vision.

Of course your mileage may vary, I've got my main in the center and the dual on the left but I've seen plenty people use a "both centered" setup.

Nordic

I can imagine the commander on the WC teams needing extra space for his 2nd monitor.