tr4head,
It depends on the contract of insurance whether one's insurance policy covers diminished value. It may be an exclusion in the policy. On the other hand, one's insurance company can be expected, under proper coverage, to pay for the repairs to his or her car. Then, the insurance recovers the money spent called subrogation.
For the average car, damage claims limited to bumper cover repairs will likely not result in any meaningful loss-of-value. On the other hand, if a potential buyer was presented with two indentical cars apart from the repaired damage, which car would we expect that buyer to choose? CarFax and other car history reporters cannot vouch, with any level of certainty, that a car has ever been in an accident.
California has laws pertaining to diminished value so there is legal recourse for a properly and appropriately documented claim. The at-fault party, to the extent of that person's liability could turn to their inssurance company and expect it to pay the loss.
Most states require insurance companies to promply and fairly address and pay for calim for which liabilty exists under the at-fault's insurance policy. Remember, no insurance means no coverage. No coverage mean potentially bad news because others can then reach into your pocket for recovery. Carry good insurance with realistic limits. An umbrella policy is an excellent, even necessary idea. Converesly, uninsured motorist coverage is nearly a requirement because so many people are driving without coverage.
It may seem that I am an apologist for insurance companies. I am not. I do not feel sorry for insurance companies, per se. It's a business and they know how to stay profitble. Who I worry about is the person harmed by our negligence and I can assure you that many poeple "wronged" at the hands of another could care less about you.
Get insurance with high limits and get an umbrella policy. Drive smart. For the all spiffy talk in magazine and TV, most of us are, in fact, average drivers. "A man has got to know his limitaions." Clint Eastwood is a very smart, very wise man. (How do you think I learned this bit of wisdom?) It's both smart and responsible to protect yourself and the interests of others who, if not for an accident would remain complete strangers.
Do what you can, but behave yourselves, y'all!