I work with logmanagemant solutions for multiple application systems. The primary issue I see with logging is that no formal standard for events has ever been agreed upon. This effectively results in a million different event formats (whatever the developers think up) and make aggregated and correlated data evaluation quite hard.

The only options that I came across is a proprietary specification called CEF (common event format) and a dead project called CEE (common event expression) which IMO was over-engineered.

From a BI view the current logging formats could as well be /dev/random and this makes logging of somewhat limited use.

It's useful though when an admin reads individual log messages trying to debug an issue.