Secondly why would anybody pay for broadband internet, and only use it like ISDN or DSL?
Ok, I have a home connection that does 40Mbps down and 20Mbps up. It is capped to 100GB/month during the day (no cap at night, and this is when I run off-site backups and such). I never come close to exceeding that cap - the speed is useful for downloading the odd film, watching streaming HDTV, uploading photos, etc. for short periods. If I need to download a new Linux distro or something, I can do it in 10 minutes - doing this stuff over ISDN would be either very painful (requiring planning a download a long time in advance of actually needing it) or just plain impossible impossible. ADSL, again, would be rather a pain for the occasional large download.
On the other hand, if I were running bittorrent 24/7 I would be able to blow through 15TB of bandwidth in a month, were it not for the cap. But I'm not interested in doing this, so I don't understand why those people who are interested in shifting 2-3 orders of magnitude more data than me should expect me to pay more in order to subsidise the build-out cost of the ISP upgrading their network to support them.
The bittorrent crowd would characterise my 100GB monthly cap as terrible because, at full speed, I could blow through it in 5 hours. The thing that they completely fail to understand is that I never have any interest in blowing through it - I like a fast connection because it lets me do things quickly, not because I can download lots.