Dave,
Without reading through the whole thread again, I didn't see anything that was drastic.
There are many various reasons for changing YOUR air pressure, such as:
http://www.mad-ducati.com/Articles/TirePressure.html
Even my car lists pressures according to the load weight I"m caring. How does a manufacturer know my riding style, roads I take, temp I'm riding in, etc,?
I'm not one to just follow a spec blindly because the manufacturer says so. Even you said they probably do set it for your safety. How can they when there is no way they can understand all the circumstances?
We're not talking of big changes, but rather in a 5% change range.
I talked to an old wheel tech once who worked where they make tires for years and then at a tire sales shop. He said there are too many variables and he just sets his to the max on the tire. That does not mean I suggest that, but just making a point.
For me, I'd rather have them slightly over or right at, than under-inflated, which really makes them more dangerous for street riding.