1/2 PINT
Just curious - grew up, perhaps mistakenly, believing that pilots tried to execute as soft a landing as possible for the benefit and comfort of passengers.
The prime objective of pilots is to land safely, no more, no less.
This is achieved by arriving at the correct aiming point, pointing in the correct direction, at the correct speed.
If you do this then the aircraft will stop on the runway the manufacturers state.
There are paramaters that limit the vertical speed and determine what is a 'heavy' landing in terms of nomal 'g'. If these limits are exceeded engineering checks are required before next flight. For this reason, I suspect that you have never experienced one.
I know that I haven't in over 10,000 hours flying.
What you have experienced are 'firm' landings which can occur for a variety of reasons mentioned. Pilots enjoy 'soft landings' or 'greasers' as much as the passengers, but they can't be done to order as landing is an art, not a science.