I suspect that this board is unusually pro-insurance. To me, there is a continum of how much money and medical care people are willing to spend on their pets, and you should make different choices about insurance depending on where you are.
Willingness to spend money
1. Cats should cost me food (does not result in healthy or happy cats)
2. Cats should cost me food and occasional check-ups
3. Cats should cost me food, check-ups, and occasional emergency money
4. It doesn't matter how much it costs, my cats are getting the best care available!
I think insurance is only a good idea if you fit into the last category. Honestly, I'm more like a 3; I think, for both humans and animals, that there is such a thing as too much medical care. Pouring money and drugs into any suffering creature is just not my style.
Any kind of insurance provider is providing insurance in order to make money. A cats' health care will cost some average amount of money, and the insurance provider will charge you slightly more than that. If your cat is healthier than usual or even of average health, if you get insurance you are wasting money. This is true of human health insurance, of car insurance, life insurance, of every kind of insurance, no matter the details of how it works. Some small set of cats will have much higher health costs. These cats, statistically, are outliers, and the insurance provider uses all the extra money from healthy cats to pay for this. The reason you buy any kind of insurance is because you can't financially deal with the risk of being one of those outliers with catastrophic costs.
I take risks; I have gone long time periods without health insurance, and my cats do not have pet insurance. But, as much as I love my cats (and one of my darlings did cost me a few hundred dollars the day she died), I would euthanize a cat with a long term, costly, painful degenerative disease.