@Quasinerdo : think the part your missing here is you can use the same material to make an AP sword or bow handle or whatnot. It's a universal system, some material happens to put AP on the item if you use it in the correct slot. There are plenty of materials when put in the same slot don't produce AP. Basically your looking at staffs, seeing this 1 instance where you could be foolish enough to apply a stat that has no effect on a staff and assuming it needs 'fixing'.
The closest thing they could do, which would require a lot of work for this literal only instance of this, would be to ensure that material can't by put into those specific slot types when your making a staff or a staff related mod item (single player you can make full staffs... maybe one day in MP too). You see where I'm going with this? Theres more then just a staff and staff related items in the crafting system. And all the materials do what they do regardless of that. Meaning the only way your getting AP on a staff is if YOU go out of YOUR way to add it on. That's your choice, plane and simple. You don't want AP on it - don't use that material, use something else in that slot... that's the whole point of this system.
So yeah it would be nice to ensure people can't screw up if they disallowed that specific item in that specific item slot when making staff related stuff and only staff related stuff... or you could stop acting like this was some horrid oversight and slight on staffs as a whole and just not use AP related materials.