So this was some little schmuck's idea of a good time. Wow, some people are just ******** beyond belief, aren't they?

I'm afraid you're going to be really hard pressed to do much for this as these look quite deep. PlastX isn't going to do a darn thing on glass, nor will most anything else you can work by hand. There are glass polishing kits out there, but they make use of cerium oxide for the abrasive and require use of a rotary buffer to do the grunt work. The serious draw back is that you can generate a lot of heat this way and distort the glass, potentially giving you poor optic quality and a wavey view through the windshield. Or you can easily generate a TON of heat and break the glass.

Much as it pains me to say this, replacing it is probably your best bet. But how is vandalism not covered by your insurance policy? Shouldn't that fall under the comprehensive coverage component of the policy?