Fair nuff, you don't worry about someone carelessly breaking your property, and you don't assign value to objects. But try and think of others that do. (OK, you probably do, but a lot of people only worry about not damaging their own things, and couldn't care less what they do to others items)
How about if I shred a Rembrant, or take a chisel to the odd statue or two? They're only things, I'm sure people wouldn't really miss them.
Yes, I would have the repair done. I happen to drive a slowly appreciating classic. It's not in good condition, but I'm doing my best to improve it. I'd rather not have my hard work ruined by someone who can't be bothered to show a little more care.
More important, yes (usually). But that's a reletive, it doesn't mean that things are without any importance whatsoever, does it?
I've done the same, but it's my property, and my stupidity. If I reversed into someone elses car, or borrowed a car and reversed into a bollard, I would expect to have to pay for the repairs.
I can't possibly comment on this without sounding like an utter bastard, so I won't! ;)