Amazon does have a remarkably fine-grained control mechanism - but you need to use it.
For example I never publish my Route53 (DNS hosting service) keys, but even if they were leaked the account is only setup on the Amazon side to work from a single source IP.
You can restrict permissions significantly, so again in my case I've got a user configured who can only add/delete DNS records - but cannot create a new zone, or delete other zones. Not ideal, since "remove all records" is almost the same as "delete zone" in practice, but I'm not worried that unrelated zones on that account will be broken if I do lose my keys.
For example I never publish my Route53 (DNS hosting service) keys, but even if they were leaked the account is only setup on the Amazon side to work from a single source IP.
You can restrict permissions significantly, so again in my case I've got a user configured who can only add/delete DNS records - but cannot create a new zone, or delete other zones. Not ideal, since "remove all records" is almost the same as "delete zone" in practice, but I'm not worried that unrelated zones on that account will be broken if I do lose my keys.