I am sure different notam items will be relevant to different people.
Even the General Hooton notam might be relevant to somebody. Cannot possibly imagine who though - maybe somebody in ATC who is watching radar and wondering what some codes are - but surely such stuff should have instead been communicated directly to ATC units, not notamed to pilots.
Gliders... should one notam a gliding site? The site should be depicted on the map with a big G. Why notam it as well? It is Class G airspace in which everybody can fly freely. Are you going to keep a better lookout because the possibility of gliders (or microlights) has been notamed?
If you fly a helicopter at 200ft then you may be interested in a 200ft high obstacle, but then there will be so many such obstacles anyway (anything below 300ft does not need to be mapped) that you need to keep a serious lookout, so why notam any particular object?
I think the reason for most of this dross is because it is easy for various people to obtain the authority to generate notams. And they generate them, lots of them. If your job involves checking the thickness of chocolate bar wrappers then it is by definition a global-level important job and if you think there is a possibility of under-spec wrappers being sold then you will notam it.