bittorrent is an impossible nightmare for people with broadband caps. To download and upload at the same time will let you reach your monthly limit within the hour.
I myself have a broadband cap, which is why I DO like torrents. If I download stuff between 2am and 9am it doesn't count towards my limit, so I just set the torrents up and let them start while I sleep. I have a 12GB a month limit, and I reach it every time. :)
There are some good answers here. Lots of reasons why bit-torrents don't suit everyone. Fair enough as well. I like all sharing methods - the hub, bit-torrent, rapidshare, youshareit, and even good old trading.