The elimination of the RewriteLog file was a poor design choice. Admins should have the choice to direct such logs to a separate file. Rewrite log out is noisy and normally not considered an "error", whereas apache error logs are more useful for finding problems with scripts and internal problems. The combined file puts greater requirements on monitoring systems, for instance, in which simply observing the file length would be more useful. The rewrite log is not only useful for debugging, but also light auditing of dynamic rules. 

Finally, mod_Security attempts to buffer output to the error file, and spits out the rewrite logs within its audit output. While mod_security can be configured to suppress lines from error_log, there is no way to selectively suppress them, reducing the value of this option.

Please reintroduce RewriteLog as an option which if set, sends the trace information to the specified file instead of via the apache logger.