You can find lots of pros and cons over at
www.cruisecritic.com as well as much great info on your particular trip- even a Roll Call for your individual cruise.
I have probably had trip insurance less that 10% of the time, but they were major internationals or times when my aging Father was ill and I wasn't certain if I would have to cancel or not.
I met a you guy back in the spring who had a sling and some stabilizers for his arm. Since we had a couple of ice storms earlier I asked if he fell on the ice... No, was skiing in Austria, clipped a small rock which sent me head over heels into a tree... Had to be airlifted off the mountain, moved to a more specialized hospital for immediate temporary surgery, then flown back on a different airline because he needed a business class seat so he could get back to the specialized hospital here. He waffled on getting trip insurance, and finally said "Ah well, just do it" He thought the bills were up over $50,000 when he last saw them, and he still had to put down his credit card in multiple places until insurance coverage was verified. Fortunately he worked for a multi national organization travel department who helped with setting up the logistics. I said, I don't know you at all, but if you did slip and fall on the ice, and that story is total BS, go with it anyway!