okay then you don't need access to anymore movies from netflix/hulu/crackle/etc, no more games from steam/origin/xbox live/playstation network, you don't need youtube (for all its own reasons), you don't need to connect your cell phone to your wifi at home, the list goes on.
The point is damn near everything uses the internet now from your home appliances to the latest tablet and everything in between. The more people find to do on the internet the more they will want to use those services they enjoy. Setting a cap is not only foolish IMHO but asking for problems in the long term. What was the average of yesterday will not be the average of tomorrow and at least Comcast understood that when impletmenting the cap of 250GB. A family of four who enjoy various forms of entertainment can use the internet without fear of running over a cap with that at least.
Then again you may be the only one using the internet at your household and merely use it for email/web surfing and that works you but what works for you doesn't work for someone else. For instance, I have a Steam account with over 130 games, not counting the free to play games I downloaded, and over the course of a month I downloaded all my games on a new rig I built. Once everything was downloaded an updated the tally was over 1.2 TB of data downloaded through Steam alone.