I think it's fairly inevitable that Entanet would have to go in this direction. They offered over-generous download allowances for IPStream connections and it was no surprise that they attracted a lot of heavy downloaders. The business model was unsustainable (even they admitted this was the case) so they moved over to WBC and changed the terms to a hardly less generous arrangement. I was with them at the time (via ADSL24) and there was a lot of anger on their forum because everyone seemed to be getting messed about, both heavy and light users.
I've thought for a long time that it's unfair that heavy users should be subsidised by light users paying the same amount. ISPs have to charge customers different amounts according to usage or include some sort of traffic management measures to keep total usage within their capacity.