While there are a couple of benefits of collision insurance, the main one is that you can file a claim and receive reimbursement regardless of who was at fault. Collision claims usually get processed faster than property damage claims because the insurance company does not have to spend time investigating who was at-fault. Another benefit is that you only deal with your own insurance company, rather than another insurer with less incentive to pay for your claim. Collision insurance can also be used toward your rental car in most cases, which can spare you from having to buy rental car insurance.
Policies typically use vague language when referring to acts of terrorism, but they are generally insured by the comprehensive portion of your policy. For example, if there is an act of terror and you need to make a claim on your car, that can only be made if you have comprehensive coverage. Since some circumstances are out of our control, comprehensive insurance is certainly important to have in your policy.