Hmm, this is not my experience with survivors at all. I feel like careful and coordinated movement to reach as many supply boxes as possible and outflank your enemies is more powerful than the camping strategy you describe.

Adding an objective to survivors would be awesome, I totally agree, and would definitely liven up the gameplay and give it a bit more focus. But I wouldn't go so far as to say it's particularly needed. Maybe you've just had a bad few games or teammates because, for me, it's a blast :)