Mick, in fairness to Maxi & others, if as well as lowering it you fit stiffer springs and decent dampers, the front of the car may end up no nearer the ground when you hit a bump than on the stock parts; as an example, if you lower it by 30mm and the suspension travels 30mm less when you hit a bump, you're no worse off. So lowering could work out OK for some; it's not the kind of ride I'd want, but that's just personal choice.
Numptys who think they can lower it on the cheap by hacking a bit off the springs are, of course, another thing entirely.
Catching the bottom of the centre box when driving over a severe speed hump is also a different issue; you need absolute ground clearance for that, and if you live in a country that's addicted to the dreadful things, it might not work out so well. I have a good friend who has a lip at the top of her (sloping) driveway and in standard trim, the centrebox clears it by only a few mm; if I lowered it, I wouldn't have a chance.
My own view is that the 500 OEM setup isn't so much badly sprung as badly damped. The later stiffened rear beam models (2010 model year onward) are noticeably better in this regard.