The maximum pressure indicated on tire sidewalls is just that - maximum safe pressure and the pressure that provides maximum load on the tire. It is not a recommendation for inflation pressures. The vehicle manufacturer sets that, not the tire manufacturer. Having said that, for most vehicles the recommended pressures are a compromise taking ride comfort, tire wear, and performance (grip, handling, under and oversteer) into account.
Tire pressures will also have an effect on how the car handles cross winds. I haven't found it to be a problem.