The G6 does have a relatively stiff stock suspension which aids handling, though it's not as stiff as most European cars. If you have the low profile 50-series tires, that will also add a bit of stiffness due to the shorter and stiffer sidewalls. Pontiac is GM's performance division so naturally it's meant to have a sporty feel.
The Camry by contrast, being a mainstream mid-size family sedan, was designed to have a softer suspension in order to provide a smoother ride for its more conservative buyers. The trade-off would be poorer handling.