You can, as most modern web services including github do, have a minimum length and complexity for the password. That's a very important part of the process yes.
Sorry, I wasn't clear. What I wanted to say is that passwords can be insecure, and in the case of lazy people that had consequences on security. I think the minimum is often not really secure, it's just "fine if you really must" but allowed to not lose to many users.
And at the same time tokens are always secure. It's not defined by the user, they cannot lazy it away, it's made equally complicated for everyone. Fortunately they don't have to type it either, it's copy paste and done.
However I have to admit that while writing this response, complexity is not really the point with github access tokens.
Plus, you seem to still not be grasping the core of my argument: github still authenticates with a password. You can still log in to the web site and change everything, if you compromise someone's password, whether because it's insufficiently complex or for any other reason.
That's right, these tokens won't protect the lazy from their account being taken over. But I think these are still more secure for their use case: storing them in mostly text files, because the programs to which you give these will probably do that, and as these are not really password-equivalent things (these have very limited access to your account), it's less of a problem.
Your original question here was how will it be more secure that we are storing these tokens in our password managers besides our passwords. My answer is that even if you put it into your password manager, that's not it's final place: it will probably end up in text files and other such places, and if such a file gets into the wrong hands you'll be in less of a trouble because of the limited permissions. If you would have stored your password there, you could be hoping that you'll get your account back, and that the person did not do anything bad in your name.
I think much of the confusion is coming from you believing that api tokens are equivalent to passwords. That's not the case. Even if you give all possible permissions to a token, it won't be able to do everything that you can do with the password through the website. In short, the main point here is that you don't have to use your password in places where that's totally unnecessary, and fewer permissions are fine.