For the record, I'm not hating on travel insurance. I'm merely providing an economic analysis of why people like me don't see it as a particularly wise purchase.
Honestly, a three day delay is excessive...even in a major weather event. I agree with the opinion that United will not reimburse any of your expenses.
That said, chances are strong that they will offer a service recovery gesture in the form of United frequent flyer miles, if asked. The easiest way to do this is the use the web form on the United site:
https://www.united.com/ual/en/us/customer/customercare
Keep it short and simple. Just 3 or 4 sentences expressing your disappointment at the extended delay in getting your party to their destination. Example:
My family experienced a 3-day delay recently due to winter weather. I understand that recovering from hundreds of canceled flights is not easy. Still, I was disappointed with the lack of options for getting my family back home.
Provided you don't complain about every flight you take on United, there's really no downside to providing this feedback.