Except there are plenty more TLDs where those 20 came from. See, all New.net's domain names are actually handled by New.net's own domain name servers. That means new domain extensions can be launched just about as fast as people can dream them up. Wait, it gets better. Almost 20 years ago, the domain name system was an elegant fix for an ugly mess.
Domain names make the Web practical and e-mail easy.
But today, there are real issues with the domain name system. Instead of 1,000 hosts, it now serves millions. It's distributed so that there's no single point of failure that can shut it down. But that means there are tens of thousands of potential points of failure - almost all managed by people whose real business is something else. Even with those bugs fixed, there are other security and reliability and efficiency problems with the current domain name system.