I think the issue is that I have a laptop at home and iMac at work so I don't bring my computer on my commute. Also, I like the extra security of the fingerprint scanner on my iPhone.
I have a Yubikey on my keychain (it can easily withstand this), and it takes very little effort to plug it into the USB port when I require it. Less than it would be to take my phone out.
As a side-note, some time ago the Yubikey had a vulnerability with its GPG module so they shipped out new ones for free. I now have the old key (with no GPG keys loaded on it) permanently plugged into my USB hub at my desktop. It is amazingly convenient.
Heck, all someone needs to do is grab the one permanently plugged into your USB hub on your work desktop after you've left for the day.
Just sayin'...
If user security has taught us anything in the last 20 years, it's that security features have to be convenient or may as well not exist. I think we'll be seeing a lot more 2FA options in the next few years. In this segment, user choice is a huge improvement in and of itself. I've also been testing Duo push for some internal stuff, which is a phone-based experience that's as smooth as silk. To each their own!