I agree that when you are at one with your boat/car you don't need gauges to tell you how to operate it. The main purpose of gauges are to warn/confirm or otherwise the correct operation of critical components when things don't feel, smell or sound right.
For example most of us know what 10, 15, 20 knots feel like, but when the speedo shows 7knots and I know I am going faster from rpm/gps/speed sensation then I know I've picked up weed or similar on the leg, so I stop and get rid of the material (which could also have been interfering with the water intake) and off I go.
Whats the first thing you do in a car when you motor starts to lose power or changes note etc? - check the temp/oil gauge/lights. Its true your senses are often the first to pick up on developing problems but your gauges then provide feedback for troubleshooting.
I see that trim tab and motor trim gauges are in the same boat ( pardon the pun) - used as a base line to confirm normal operation and alert to other possible problems, not used to unquestioningly set the running attitude of your boat by.
Cheers FM