When I do LOS, I like to put part of the wall within the LOS field because I think the texture and visual details add depth and context, but that was just how I personally preferred it. I understand why the literal interpretation of Line-of-Sight would indicate that the occluding would be done right on the edge. That said, when I was doing Agents, Unity and LOS was pretty new and I think I was experimenting in that particular period of the advanced techniques for LOS, et al. I definitely altered my approach later on (when I did AV).

So yes, I agree on having some technique available for seeing those edges.