I believe the default smb.conf file should contain "client ntlmv2 auth" option, maybe commented out if needed, with appropriate comments... because it's tedious to add manually it every time when Windows Vista and later machines is used.
maybe this is something you should ask your distribution package provider to change there.
No. Maintainers just package whatever you shove at them and do not mess with configuration files. Plus, how not having very important parameter in config file which appears self-documenting, is "invalid"?
Thanks for reporting! Samba ships example smb.conf files. These examples cannot meet all needs. And it's still a configuration file, not documentation. That's why I am going to close this one as won't fix.