I don't see why that's a problem? If you've created and released better software, why wouldn't you want your users to update?
The Bitcoin Core developers want users to update at their own pace whenever they feel comfortable updating. This is because new versions may contain consensus changes that users may not agree with, possible security considerations that users are not comfortable with, etc. By using an alert system to inform people about new versions, we would be pressuring users to update and we do not want to do that as that violates the principle of letting users upgrade whenever they feel comfortable with the changes.