The MITM to make you agree to a pointless EULA for using wifi is one of the most obnoxious things going. I know this trick (I've usually used http://fark.com) but non-technical people don't know it and as such public wifi is largely useless to them because of the MITM they use. Also, plenty of public wifi is flaky and as such by the time you've loaded the authentication page, you've lost your signal and need to re-auth!