NAT:ed addresses means that the customers' (private) address is not reachable from outside the point in which you do the NAT. This point resides within the primary (point of sale) operator's network.
Now, say that an ASP wants to offer some service to your customers (generating traffic = revenue) which has a communication pattern in which the ASP needs to connect to the customer's PC. Because of NAT, this is not possible.
Yes it is, you just have to put in the configuration.
A common application is remote access by IPSEC connections from mobile/residential users to the office. IPSEC+NAT is not a good combination. It has been known to work through NAT under some special circumstances, but typically gives you problems.
This is true.
The fact is that the customers' addresses are not reachable from outside the NAT:ed area. This limits your ability to provide services to your customers.
Some services yes but not all.
NAT may be used successfully in some scenarios, and unsuccessfully in others. In my opinion, it should be every operator's choice whether to deploy NAT, and not regulated by eg RIPE, and hence should not be considered as a solution for the "always-on" allocation problem.
I 100% agree. Neil.