In my opinion it is situational, and honestly if I don't think the guy can get up and get to cover before getting shot again I wont even bother trying to res them and just avoid the area being camped. Situations like this are common though, I know from personal experience (the hallways in Damavand Peak for instance) that there is a time to just let people die. However when trying to cap a point I feel it is always better to go for the revive instead of waiting for the camper, who is usually preventing the cap to kill you as well or holding it for his buddies to spawn.
I know as a person who plays medic most of the time that I have done it on occasion, however it is usually as an effort for the guy to inch out of the camp zone into full cover. Also for those of you who have this problem dont accept the res instead when they first revive try to crawl into better cover before accepting, imo it helps to eliminate the scenario completely as you either make it to cover then accept the revive or just get killed again and be unresable.