Is there a reason why takeoffs and landings are so bumpy for passengers but not for pilots?

The pilots, perhaps, have more perspective on what “so bumpy” means. A firm landing doesn’t mean it’s a bad landing. If the runway is wet, the pilots will want to “plant’ the wheels on the runway to avoid aquaplaning. An extremely smooth landing can mean that the plane “floated” down the runway past the typical landing point.

The pilots and crew are on the same plane and if the landing is excessively firm they know it.