I think you're just unlucky. In over a year flying on it I've only experienced a handful of "firmer than usual" landings (seated both aft and fwd) usually due to weather, and in one case due to a bird choosing the wrong place to be at that critical moment...
Could also be down to past types flown, but you guys would know more about that than I.
Have also experienced a few where I hadn't realised for a few seconds that we'd actually touched tarmac, credit where credit is due
