I think you are missing the point, required by law does not stop things from happening. A proper system stops bad things by having multiple layers, at present having a one point safety net that can either be undone by a council not submitting the notice or the pilot not reading the notice is a bad system. The MOS has fixed most of the problems regarding extra signage required, but the NOTAM system is still flawed by a number of issues including overwhelming information, which in itself blocks critical information from being registered.
Saying the current NOTAM system is adequate is like saying, oh we don't need ATS, TAWS or Radar, pilots are legally required to know the lowest safe altitude and can make the safe choice themselves to let down to an airport if IMC. And separation, the law says I shouldn't hit another airplane so, that should be it, I don't need TCAS and ATS services, get rid of those costly buggers, I have a radio so can talk to others and separate, I don't need fail safes, I'm a Skygod.