Are you kidding? I'd do 200GB a month if I had tethering on my phone. Yes I would get my every penny's worth.
Right now I do about 2GB a month just on the phone. I use 3G only and never use WiFi; I'm paying $65 a month just for data; that's more than twice as much as almost everyone else. I'd get my money's worth and I applaud anyone else who does the same.
If any SP can force fees like highway robbery, consumers have every right to use the service as needed.