As a power user, it's easier for me to invoke my password manager than it is to open up my mail client and copy/paste in a one-time key.
If not, this might be a good second option for a site to have that doesn't involve you resetting your password:
First option - normal password Second option - email one-time key Third option - reset pw via email (if you really need to)
Any accounts that are accessed on other people's computers should be unimportant (e.g., email accounts that aren't associated with financial accounts) because those computers could be compromised. Unimportant accounts don't require strong passwords, so a password manager isn't needed for accounts that one might access on other people's computers.
It's much much faster than opening my email, and waiting for SMTP & Gmail to get its act together.