I can't even recall how many times I'm out and about and I meditate to make some potions and I think, "I could really use some traps." It just seems to me like one of those items you could put together "on the spot" if you had the materials.
I would love to see these functions implemented ingame. I like how you can sneak around in Witcher 2, but it sucks that theres only certain areas you can use it in.