I had the Prestige card since the beginning of time, but dumped it recently despite them offering me a $450 credit to negate the annual fee. While I never used the travel insurance benefits, it sure was nice knowing they were there. I had used their roadside assistance, which was a nice perk. However, I moved on.
If individuals don't frequently use the insurance benefits, I can't image the costs are significant for Citi. They may even be self-insured.