You obviously missed the point of it's real world use. People who use a ton of data, aren't going to want to wait on a 3G connection to get it when they can have much faster in their home. It's really only handy for the few times you are away from home and need the net on a laptop or want to show off. Yes, there are people who still cannot get internet in their homes that is much faster than 3G, but those are few and far between. And chances are, if they can't get highspeed in their location, they'll have a crappy 3g signal as well.
The latency over 3G isn't something a gamer would want to put up with either, so they would look for a more dedicated form of access also. Hell, it's really not even fast enough to stream a lot of internet content aside from music and low bandwidth (ie: pixelated) video.
Of course there are going to be freeloaders who will use their phone for access, put up with all the negatives, simply because they're too cheap to get a real internet connection. These people don't make up a number big enough to even matter in the grand scheme of things though.
Charges for data over the cell networks have always been obscene, and this practice has not changed at all over the past 10 years (guesstimate). It does not cost Verizon near what you think it does to provide this bandwidth, but since they can get away with charging whatever they want, they will continue to do so. Who honestly believes 1 MB is still worth $1.99 if you happen to go over on your limited plan? It costs Verizon maybe 1/100 cent for that tiny amount of bandwidth.
Going on your example, what's to stop people right now from downloading mass amounts of data directly to their phone? They don't even have to be tethered. But as it is now, they could download 10GB directly to their phone for the $29.99 data fee, but if they want 1GB on their PC they have to cough up an extra $20?