People are too used to the old domain name extensions. They have a hard time picking up the new stuff. A clear example is the fact that the .com extension is the first one people try if they do not know the extension of a website.

Also the cost of a custom domain extension is way too high for most of us. Still I am wondering who will swoop the .sex domain. Now that will be a good investment, regardless of the money. If I had the money i would buy it. You can never go wrong with online mature websites.