Why is VMS so good?

Joe Bednorz sent me a couple of mail messages where he writes what he feels about VMS, and it pretty much compare to my feelings about it. Here's a summary:

There are several things that make up a good OS, and VMS has most of the features:

User available features:
• Very good documentation.
• Very good help for users.
• Consistent commands and command names (like SET to do all kinds of settings), and one CLI with all the features you might need (who needs sh or bash, or tcsh for that matter?).
• Consistently made editors!
• Logical names, definable on system level as well as on personal level.
• Error codes that are consistent, and uniquely identifies the problem at hand! And mapped to them, messages that have a meaning. And also the ability to have sub-error codes and sub-sub-error codes.

Programming features:
• A great debugger.
• The common language independent routine libraries.
• All kinds of extra products to help you when building programs, link MMS, CMS, FMS, ...
• The file system, RMS! It includes indexed files, which can be changed by several users at the same time.

System features:
• A robust file system!
• No partitions (there's no need!)
• No need for suid and sgid bits.
• A backup utility that can handle and get past tape errors (and even recover the erroneous bits).
• Backup dates on files!
• Computer interoperability over networks (clusters, even competing companies will admit to the superiority of Digital VAXcluster (which should really be called VMScluster)).
• SECURITY! ("What? No world-readable passwd file?")
• All kinds of monitor capabilities.
• Process privileges! You can delegate responsibility in small parts! No need to give the lowly operator access to the whole system ("What? No 'root'?").
• Rights identifiers! Give selected users (from many groups) the possibility to share a project, account-wise and so on.