These threads are a lot alike: Some people say belly pans are unnecessary, and others swear by their skid plates. And I'll chime in, as I usually do, and say that neither my sons or I have ever had any problems with factory belly pans on cars in New England. Between us that's over a half million miles of driving. The original on my wagon finally gave up the ghost two years ago, replaced it with one of the lightweight aluminum ones we sell, and all's good. My younger son even got run off the road last winter in Western MA in his '00 Golf and didn't break the oil pan. Maybe we're lucky. But one thing a lot of skid plate fans don't mention is that most plates end up closer to the ground than the factory pan. So of course it hits things, things that you'd probably go right over if it wasn't there. We bought my son's Golf with an Evolution skid plate and it was very close to the road, although, like everything else on the car, it was probably installed wrong.
But I know I'm not going to change any minds here. The only thing I will add for the OP is that the belly pan (or skid plate) keeps your turbo, alternator, A/C compressor, power steering pump, and other bits cleaner than they would be without it. Sure, someone in SoCal can drive around without one, but in New England I think it's helpful.