What's the attack vector you are protecting against that a good, non-reused password is not covering?
Still, when you've got access to your password manager (to get your password and TOTP token too), you've got access to a trusted device too.
And there is still an option for anyone (including shoulder surfers) to type in your password+token a bit faster than you so they get in: nobody bats an eyelid for getting reprompted for another TOTP token.
You are also vulnerable to someone stealing your password manager password in this manner, especially with a cloud one (which is what most businesses require).
As a conclusion, it does grant you some extra protection against using password only, but when on a separate device, it's really another dimension.
A random thief stealing my laptop would have to:
1) Bother
2) Break my hard disk encryption/know the password
3) Break my password manager encryption/know the password
I think that's hard enough for someone wanting to get into my email. I use a separate hardware key to secure my domains, and that's about it.