I am certain there is already a spotting mechanic based on range, terrain, weather, experience, optics etc. There is absolutely no reason for it not being in the game. What you are suggesting is something akin spotting action from the hex based wargames, like the horrible Squad battles series from John Tiller.
To make it more interesting, the order could be activated through platoon leader only, assuming he's the man/element that would normally scout/judge the terrain for the troops anyway.
Why would a platoon leader be the only man that would normally recon for the troops? Squad leaders are perfectly capable of such a feat, as well as any couple of soldiers, that a platoon or squad leader could send anywhere to check on suspicious objects or elements of terrain, as well as provide some form of security.