NAT is more expensive to produce, so it should be an optional premium service, and that seems to be more and more the case.
Not necessarily when you consider the cost (in bandwidth, network reliability and support staff) imposed by worms and kiddies from other networks scanning your IP space for unsecured machines. That's not even to mention the cost imposed by compromised systems. Even if NAT only reduces compromised systems by 20%, that's a cost savings. Given that most edge hardware supports NAT, the additional cost is nominal. Getting IP space allocation is not without cost either. Adam PS. Is this off-topic for NANOG? If so, I apologize. Given my networks are repeatedly the victim of distributed DoS attacks from compromised machines on other networks, it seemed relevant to me.