I think some of the changes are reasonable:
1. restrict the insurance to the primary cardholders immediate family
2. have a small deductible (~$50-$100) in order to avoid a flood of tiny claims that cost x times more to process than what they are worth
But some of the changes are just ridiculous:
3. cover only for segments of a journey that are fully prepaid with the card
4. restrictions regarding medical history
5. exclusions of perfectly normal "everyday" activities by classifying them as special sports
6. a deductible of $250, that's more than it costs to buy an individual travel insurance
When I purchase a travel insurance individually, it covers my travel no matter how I pay for it. The AMEX platinum charge card costs significantly more than most other cards with a good insurance cover. I expect that the additional fee includes a full travel insurance, similar to ones sold individually. The purchasing power of AMEX should ensure that they get a good deal on a full travel insurance for their cardholders and this cost should be covered by the annual fee. This should not require prepayment of every segment using the AMEX card, which is in many cases completely impractical or impossible.
Likewise, I expect this travel insurance to be as good as the ones I can buy individually (or at the very least as good as insurances offered by cheaper credit cards), that is it should have similar requirements to medical history and similar exclusions.
If ACE insurance insists on these silly changes, AMEX should just cancel their contract with them and negotiate the bulk purchase of family travel cover for all their cardholders with a different insurance company. Alternatively, everyone should rethink the value of the card and cancel it if it is not worth it anymore.
If they do implement these changes, this significantly reduces the value proposition of the card. Basically the insurance becomes worthless and it is better to purchase a travel insurance individually. Therefore, the value of the card is reduced by the cost of a full travel insurance for the cardholder and the immediate family.