bigblackboxx, you've clearly been doing your research! Yeah, we're actually not using IndexIgnore. Instead, we're using something more along the lines of the "File" tag you listed above.
Though I didn't personally set up this configuration (it was auto-generated by cPanel), I have a guess as to why they constructed it the way they did. IndexIgnore will prevent the error_log from being listed in a directory page, but it will still allow that file to be downloaded or looked at. Since "error_log" is the default filename for any file containing Apache errors, without the "File" tag directives in httpd.conf a hacker would be able to often glean crucial information just from guessing the existence of an error_log file.
However, with our current configuration it is impossible to read these files.