From my perspective, if there were a way to disable anyone from using the login of 'admin' or 'administrator' when registering, that would be awesome.
WordFence already does this for "admin". Just check
"Prevent users registering 'admin' username if it doesn't exist"
For anything more complicated, you might try https://wordpress.org/plugins/restrict-usernames/
I have clients on the road all the time. They blog from various locations. If they f-up their login multiple times and are locked out, they call or email me to unlock. I ask them to identify their IP address by using a source like http://whatsmyip.org. I then go in in and identify their attempts and unlock them. A one time error like this is a freebie...but if they continue to do it, I charge them my going rate.
I'm not really interested in trying to find excuses to charge my clients for things like this. Anything that requires me to be "on" all the time is simply not worth the fee that I would be able to charge. My login cutoff is forgiving enough unless they're really drunk or something, in which case, they understand that I can't be on hand to fix things until a reasonable business hour.
if it comes down to your REAL users forgetting their usernames... my feeling is that if it's a one time thing... BFD!! If it's every time they travel, train them by charging them! They'll learn!
Once again, what people are talking about here is ways to improve targeting logins you IMMEDIATELY want to lock down. People forgetting their usernames isn't really in the scope of the discussion, and WordFence already provides adequate options for dealing with legit users who are bad typists.