I can't remember the last bike I had that there were different tyre pressures recommended for 2 up, but some did have recommended suspension adjustments, either manual mechanical or electronic.

My Mk1 Triumph Tiger 1200 had the "usual" front 36psi / rear 42psi recommended but the Mk2 it was lower pressures. I questioned Bridgestone about this and they said to ignore the Triumph handbook & use the usual 36/42. I happily took their advice as I knew the Bridgestone rep had ridden exactly that bike round the Nürburgring at "significant" speed without issue.

As a whole I agree the recommended pressures should be a base line and I adjust pressures to my preference according to road/weather conditions. With the tyre pressure monitor systems on modern bikes it is informative to see how the psi fluctuates with temperature.

One thing I have noticed is that big/heavy modern adventure bikes tend to suffer slightly weird front tyre wear. The profile gets, ahem, "worrying" long before the tyre wear indicators are reached. I guess this maybe due to their weight & large 19" or 21" front wheels with slightly off-road orientated tyres being used fast & hard on tarmac.