To each his own. But playlists, although useful for playing, are a terrible way to organize and catalogue music. I wouldn't expect playlists to be changed as you'd prefer; it's at odds with the design goals of MC.
You'll get a lot more out of the software if you tag your music properly. Then you can have views for whatever you want: composer, soloist, period, instrument, composition type, etc. and it will be presented how you want, not as a primitive list.
Hopefully you realize that to do this you don't have to tag things individually. If you already have all Baroque music in a playlist, just select everything in that playlist and you can tag it all as Baroque in literally 2 seconds in one step. You could likewise tag instrument, etc. so it would not at all be time consuming.
If you've already done he hard work of deciding what is what (by organizing into categorized playlists) then you're just inches from the finish line.
Good luck...
