Having 90 PSI coming into a home is ludicrous, although NYC plumbing code state that if the pressure exceeds 85 PSI it had to be reduced to no more then 85 PSI and even that kind of pressure is uncalled for unless you have fire suppression system then I would allow the 90 PSI to be used for this only and then reduce the pressure right after the fire protection connection.
Excessive pressure can cause hydraulic shock (water hammering) and in the case of ferrous and non ferrous metal piping you can have serious erosion problems especially with copper.
Here are some examples that 90 PSI are capable of
1- 90 PSI will elevate water to a height of an astonishing 207.9 feet (neglecting friction losses)
2- The velocity would be 33 FPS which is over 4 times that recommended for copper tubing
3- If a 1" pipe should burst you would have water flowing at a rate hovering around 82.5 GPM (full flow)
Your hot water heater builds up pressure as the water is heated so now your looking at the T&P going off or you will need an expansion tank to allow fro the pressure build up
If you have a washing machine with rubber hoses you are straining these and looking for a plumbing disaster
More is not necessary better in this case.
Just to arbitrarily allow 90 PSI into a home is just plain irrational as you gain anything but a very strong shower.
Pressure should be calculated as to what your needs are.
For example one takes the height of the structure where the highest waster supply is needed and figures the static pressure so they have an idea what the pressure loss is, then one looks at the manufactures literature to find what pressure range they suggest like a flushometer needs no less then 35 PSI ( depending on model)
I know this maybe hard to comprehend but there are a lot of self proclaimed "plumbers" who have no clue to formal training and never would think of finding out why we size piping according to fixture demands and friction losses.
It is like going to a doctor who learned by on the job training and never bothered to go to medical school as schooling is for nerds who want to actually learn the why and how's of decent plumbing practices.
Good luck ..... By the way do you happen to live outside the USA?