The problem with proxies is they work on a flase premise. The false premise they work on is that external bandwidth is expensive - and thus it is worth spending time money and resource on reducing external bandwidth requirments. It is very like the false premise that 'storage' was expensive - that led to people coding year date fields as 2 numbers and not 4 - well into the 80's and beyond, thus creating the y2k problems.
I would challenge anyone to prove to me that the cost of running and maintaining the NTL proxies is less than the amount saved on external bandwidth costs. If you add in a cost for the problems these proxies cause for users as well then the figures make even less sense. Of course you can also use such proxies for other objectives - like limiting what and how much people can browse but that is apparently not the objective for NTL.
PS there was an onlinbe petition setup a while back - but it's not had much support so far so maybe NTL's forced proxies are not that much of a problem to most users?
http://www.petitiononline.com/ntlhpp/petition.html