Yes, this has been requested before, it is on the todo list.
In the meantime you could do it manually as follows, it might be worth the effort.
Set the Preferences as required for Popular Music
Edit Jaikoz
Copy settings.jai file in your home directory
OSX
Go to Home : Library : Preferences : Jaikoz
Copy settings.jai settings.pop
Windows Vista:
Go to C:\Users\username\Jaikoz
Copy settings.jai settings.pop
Linux
Go to $HOME/Jaikoz/Prefs
cp settings.jai settings.pop
Now restart Jaikoz again, change settings to classical options
Close Jaikoz and rename settings.jai agaqin.
Now you can use classical or pop settings by replacing the settings.jai with the reuired one, and restarting Jaikoz.