How so? I would keep this on a keychain or lanyard (it looks rugged enough to handle that sort of environment). When I need to authenticate, I plug it in, when I'm done, I unplug it. That seems a lot more secure than leaving it in the computer all the time. If someone gets my computer and the YubiKey is always installed, that sort of defeats the purpose of having a separate hardware security device. In that case, why not just use Keypass?
I've had the standard USB version on my keys for about a year at this point. They're in my back pocket and take a bunch of abuse. Still works just fine.
Direct physical access to your computer is not the only thread. Even if you have in your computer all the time it gives you better logins, easier and safer. Specially protection from phishing.
When I leave my computer out of my eyes it usually locked (unlock with password), so I don't expect somebody to quickly go in and do something. If I leave for longer, I sometimes pull the Nano out and put it somewhere I don't lose it for a while.
The advantage of your system is that you can use the U2F screen unlock instead of the password.
How so? I would keep this on a keychain or lanyard (it looks rugged enough to handle that sort of environment). When I need to authenticate, I plug it in, when I'm done, I unplug it. That seems a lot more secure than leaving it in the computer all the time. If someone gets my computer and the YubiKey is always installed, that sort of defeats the purpose of having a separate hardware security device. In that case, why not just use Keypass?