Travel insurance?

So my fiancé and I booked a 5 day vacation for our friends destination wedding in the Dominican Republic. All-inclusive, airfare, ect totals $3000.
The travel agent offered insurance for a full refund in the event we couldn't go, and it costs $334.
I think it's a waste, but she's wants piece of minds if we had to back out. I don't see any scenario where I don't go. Even if our friend cancels the wedding, I'm going to the DR.
What are your thoughts on travel insurance?

For your troubles: Phone Post 3.0