>>know exactly what's going on

Why? Once you've got over 3 Bar of oil pressure, that's plenty. How would it affect any driving decision to know whether the oil pressure is reading 3.5 or 3.7 Bar. I like the pegged needle, it's much better than having a needle yo-yoing back and forth.

Also, having a 3 Bar range allows the gauge to be more accurate and sensitive for reading the low pressures when things do become critical. I'm happy that my gauge would allow me to check to see if I have over 0.3 Bar at hot tickover, where a full scale reading gauge would never provide that sort of (useful) information.