When you upgrade from a scooter to a 600CC sports bike, don't you want to throttle it a bit faster, further, or longer? You sure you'd ride it just the same as when you were on your old scooter?
Sure .. same distance does not require further mileage. But having a speedier bike, you'd change your riding style. Given a more powerful engine, you'd want MORE. More distance, more mileage, more everything. The Need For Speed(TM).
In the old dial-up days, a 5 MB MP3 file used to be a massive load, Oh crap then I need to find 4 floppy disks just to fit it in! Today? Yes 5MB today is just as big as 5MB in 1998, nothing's changed .. except you don't feel fear or threatened by it anymore. You can get it in a couple of secs today, just as fast as you can get 50kB of data back then.
So yes ... faster network will lead to increased usage. Sooner or later.
Not that hard to understand, does it?