Not necessarily a 'bad hair day' for the pilot. Not every landing has to be a 'greaser' with the main gear lightly kissing the tarmac. On a wet runway, for example, with the risk of aquaplaing, it is sometimes better to make what is often referred to as 'firm contact'. Holding off in the flare also reduces the amount of stopping distance available.
As far as noise is concerned, sitting behind the wing in a 737 will be noisy in the cabin, whereas the DC9 has its engines mounted at the rear, behind the passenger cabin, hence the low noise.