Good on Google for pushing things forward.
When you hear of some of the horror stories it's amazing that other major providers don't even offer two-factor auth on their email products.
Yes, the intermittent requirement to authenticate via app or phone call is irritating, especially when you have multiple devices that are in a constant state of flux, but the alternative is far more troublesome.
The main problem is the classic 'explain it to your dear old mum' quandary. How can I express the benefits of the likes of one-time passwords and two-factor auth to her in a meaningful way that allows her to
a) take the benefits on board, and
b) see that they outweigh the inconvenience
And that is before expecting that she'll actually be able to navigate what is, for most people, quite a convoluted process to get it all set up, plus the ongoing maintenance.