Why would this force people to use more C4? Barricades can be destroyed by a few pickaxe swings.
I've seen people place barricades around their outer walls, but I always thought it was a waste of wood?
2 c4 to blow up the wall, 10 seconds to break the barricade with a pickaxe, and you're in.
Unless placing barricades behind walls somehow makes walls stronger?
Anything behind the wall you're C4'ing like Stairs, Crates, etc. absorb a lot of the damage C4's produce, thus putting the barricades inside your base and behind your walls (not outside of your base) prevents raiders from hacking at them and have to use more C4 to clear the wall.
Unless a patch changed things.
And yes, they also help reduce how much people can see inside your base, so they can't peek around to see which room has crates and which room leads to a dead end, etc.
Even inside my base when there is a bare wall, I place a barricade against it. It's just one more thing for raiders to have to deal with. They will either have to use more C4 to blast the barricade before the wall comes down, or the wall comes down and they're faced with a barricade they have to get past.... so they either use another C4 or end up having to hack away.
But as every room in my base is a 1x1 sealed off area, they have to keep repeating this process until they finally make it into a room with anything of worth..... and if they picked my bigger base that's just a decoy and has nothing inside.... they're going to end up royally PO'd.