I think people know how to use them properly, but It is not practical to change your "outfit" between each match. Unfortunately, we do not have the option to choose our clothing for each loadout. If we did, I bet you would see fewer people running & gunning in a ghille. I run & gun on most maps, but snipe on a few, and am torn between which clothing to wear.
In response to the OP, I find that the ghille is more visible than other clothing options on maps such as Sovereign & Strikezone. Of course there are a few spots in such maps where a ghille can hide, but there are not many. Personally, I love the addition of the ghille, especially for snipers on maps like Stonehaven and Siege. I also love that you CAN hide in the grass. It drove me bonkers that you could not do this in the last couple of COD releases.