You're not too bright are you? Do you think the united states is the world? There will never be a time where every country will adpot a law that will state all adult materials must be on .xxx. Also some countries have a very vast difference of opinion on what is adult material and what is not. Xxx is useless when it comes to blocking. There will always be porn sites on .com,nets, ect. ICANN doesn't want to be policing content and there are just too many issues with this extention. For example, if all adult material was forced to be on xxx then the .com owners would have to the right to own the .xxx version of their .coms. With every other tld this isn't an issue because no one is forced to do business only on a certain tld.
Not to mention at 75 dollars per domain its total extortion. As someone who would of had to fork out at least 15k just to get the xxx version of my .coms (if i would even be able to get them since so many huge corps with huge pockets would be buying up every intelligable name and no average person would really stand a chance) I am happy it didn't pass.
Bottom line in my opinion, is if you think xxx is good idea because of blocking, well those who are proactive with blocking already use blocking software, and those who don't, still won't do anything about it. And those sites who don't submit their sites to blocking software or other such tactics would never use .xxx. There will always be countries and hosts/registars would would host such things, just like spam, viruses and the like.