So what kind of insurance do you get thru work??? Health insurance? That's my guess. As above, look at YOUR policy, not just the company that your employer uses. Many health insurance policies do not provide coverage outside of the US.
Some credit cards provide
travel insurance automatically if you used their card to book your trip--again, fine point.
Is it worthwhile to buy travel insurance? Well, statistically it's a bad gamble (if it weren't, the insurance companies wouldn't make money). However, look at the post from the woman who had a son evacuated from the ship last night--while health insurance may cover the cost of her son's surgery, it is her travel insurance that will pay for HER to remain with him and ultimately get them both back to the US when he is able to travel.
So...20+ cruises. We had one cruise affected by Hurricane Jeane--expenses were additional hotel rooms, meals for those days (
DCL gave us a partial refund on the cruise). Was that more than the insurance cost--yes. One trip to medical center for DD--that time, the insurance reimbursement was about equal to the cost of the travel insurance. So yes, the insurance company comes out ahead in my case, but I'm OK with that.
Look at getting insurance privately, not thru DCL. It is usually a lot cheaper, covers more, and often provides a free child's policy with each adult policy!