Actually, it WAS the default, Linda. Got many a user.
Don't know if it still is the default - but it was definitely the default for many years. It gets set 'encrypted' when one first fires up Outlook, it completes it's installation, and creates the main .pst file. It had to be manually changed to bypass it - it wasn't even an 'installation' option.

Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good ...