That's unfortunate, but no, Verizon is not going to offer any help. Any damage to your phone and they will not warranty it. So, be glad you purchased insurance and can get a replacement for only $100. It's impossible to know why your screen cracked, but I think most cracked screens are probably stress fractures from carrying the phone in a back pants pocket or somewhere that puts the screen under stress. Anyway, I'm sure that's the logic Verizon uses. Maybe you'll have better success with your replacement phone.
I havent had any issues with my Droid RAZR but I am having a ton of technical issues.
My best guess for the cracked screen is the heat that this device puts out! It goes well over 100 degrees for me and as high as 120 degrees!