Rational, maybe-in this litigious society, everyone with a substantial insurance policy or bank account is a target-it is still counter productive, in my opinion-might as well call it retail malpractice insurance.
I prefer to stick with the small companies and customers-neither of us have anything to gain from lawsuits but ill will. I was a workers comp case manager too long to be a fan of litigation over stupid stuff...
If the company providing the service can rely on the homeowners to have adequate liability insurance then they probably would not have to insist.
You know how real people are.