The ESTA and new $10 fee will
eventually replace the green visa waiver form but, as syko points out, it is going to take them some time to get all the right mechanisms in place to collect and store the info and fees.
I'm seriously hoping most people don't see this as a new 'tax' on US visitors (although it could certainly be construed as such) as it will go a long way to making the whole US tourist process more visitor friendly, with new training programmes for immigration officials and better (and quicker) arrival procedures. This has been a HUGE issue for the US travel industry and has taken a lot of work to turn into law, and the fact is that the tourist business will have to match every $ that is taken in fees, thus ensuring their international marketing and, more importantly, their ability to lobby on behalf of tourist issues, is a lot better than it has been.
And just as a point of comparison, Susan and I are just back from a trip to Chile (pre-earthquake) and, as an American visitor, she had to pay a whopping $136 'reciprocity fee', in cash, on arrival

As a UK visitor, I escaped the 'fee', but it does give you an idea of what other countries already charge for things like this, and it does make you wonder!