Previously, you could opt in to Touch ID for the vault. Now, you cannot disable it. This is indeed a significant problem. One example only is that an overzealous law enforcement officer might coerce vault access via fingerprint. They would then have access to all vault content. If a password were used, at a minimum a court order would be required to obtain vault access.
The very word "vault" implies an area of higher security. Just because someone has a key to my house does not mean that they have the key to my safe. I would posit that virtually no one would have a safe key that is the same as their house key. Norton has just in effect done that very thing.