Given a choice would you prefer a traffic shaped network or not? at the moment it is extremely easy to break their limit, using my connection for approx. 30 mins gets my speed cut in half. Simply saying it's unlikely to affect me so i don't really care is a bit weak, what about when it does affect you? say all of a sudden you find a reason to use your "high speed" connection and find that you are only getting half what you are paying for when you want to use it.
in my opinion, the 2/4mb limits are too low, i think at the least all levels should have the 3gb limit although i'd prefer no shaping at all. it seems to be a means to an end in pushing out the 20mb service and anyone using a 20mb connection that doesn't download more than 3gb on atleast a semi regular basis could do just aswell with one of the lower tiers. if it wasn't for people like the OP we'd probably all still be on dial-up paying by the minute