Personally I turn filtering down, since I think it is always better to have the sharpest information possible and rather blur it in post if I need to do so. You are propably right about it not being very close to photography at all, but we all want to make awesome pictures. ANd I bet if a real camera would be capable of delivering such sharp pictures, everyone would make use of it. Just because something doesnt work in reality doesnt mean that you might not want it in your CG renderings 