Hardly useless, search engines still use the domain name to gleen information about site content. Google says they no longer do but I can find countless domains that are exact match even after the EMD updates. I couldn't get the example.com I wanted but perhaps I can get it in .wow or .cool
If the web was restarted there would be only one tld and you wouldn't need to add it to a web address, wouldn't it be cool to just type in webmasterworld and get here? Since the web cannot be restarted without massive issues then open them all up and let people choose.
The security types who monitor and record people's online behavior will have to update their systems to monitor infinite TLDs but that's quite honestly their problem at this point.