This is about as far from a server installed with ubuntu in 2012 that one can get. You are not going to find any such article by Schneier promoting default firewall installations. I suggest here to check out Secrets and Lies by Schneier, as it is rather clear that a firewall need to be configured against the specific threats one can identify. If you fail at identifying threats, the firewall is likely not be useful at all, or will simply work identical to NAT. At worst, it will give a sense of false security.