asterisk users - Dec 2005 - Why does musiconhold.conf changes require a reboot?

Hi,

Why do changes to musiconhold.conf require a reboot. Also if I put mp3's 
into the /var/lib/asterisk/mohmp3 directory will the be played if I use 
the -r option? Using Asterisk 1.2 and have run the make config in the 
/usr/src/asterisk-addons directory.

Thanks