I still don’t see the problem. You copy the password before hitting Select (the password generator page is still open after copy), then save the entry. Then you can go to the page and the password is in the clipboard ready to paste. Just saves the extra steps, which is your stated intent.
Right, but every other password manager I’ve used will save the state if the app is left, allowing users to bounce between manager and an app/site while creating a new entry. Unless there is a security reason not to do this, it should be allowed.
Use case: creating a login with password restrictions. Generate password, paste in site, rejected, generate new password, paste in site, rejected … … account creation, save in Bitwarden.