Stating that the airbag would be useless due to the cracked windshield is sort of an embellishment. If the windshield is weakened and is broken by the airbag, the airbag’s effectiveness would be reduced, but it would not be useless. If safety is important, replace the cracked windshield. They’re not terribly expensive for common vehicles. I will be having mine replaced soon on an '02 Grand Cherokee, and it will be under $300, parts and labor. Getting hurt or killed sucks bad enough to make the $300 worth it in my mind to lessen the chance of either happening in the event of an accident.