Yes, this is something that always bugged me. One other problem related to this: You can open the extension in a new window but then also all info typed in is lost and the URL-field gets filled in with a useless “chrome-extension://…” URL.
Edit: Maybe you could add an option that clicking the plus for a new login always opens Bitwarden in a new window (not tab) with the correct URL passed in. This way you can’t loose information and have the ability to even switch tabs.