Yes, because it is a pain. Try going on a vacation, you know the one where you don't use cell roaming. SMS is out, so then one must find a Wifi hotspot to use one of the smartphone time based tokens (edit: seems the token don't need a network connection, could have fooled me). And those time based tokens go out of wack if your phone didn't sync the timezone properly to match Google's setup, so every token ends up not working.
Use the print out backup verification codes on a piece of paper? No, because they are single use. So you end up using up all your backup codes depending on the length of your vacation. I've used 2 step for a long while, I liked it, but I really could not get used to whipping out my phone every time I needed to check something related to Google.
I've had other hiccups such as mobile provider down, phone died etc. Maybe my best option was to keep all the backup codes on hard plastic with checkmarks next to used backup codes and secure them the same way I do my banking cards, maybe, I'll just try this one day.
If one is going to jump through all these spy-style codes might as well just change your password on a regular basis, forcing all previous sessions to invalidate.