No, most people don't log that much. But it's nice to know that you can, if you have to, turn all loggers to DEBUG, or even TRACE, in production without hurting performance. With old-log4j and logback this often isn't possible.
The performance isn't an across the board improvement, as far as i've understood it, but just an improvement that comes from removing all the little contentions from synchronised blocks. I can imagine that this appeals to the c* community, even if it's of little practical meaning for normal production c*
Log4j2 also provides the auto-reload of configuration files. Other features it offers is at http://logging.apache.org/log4j/2.x/