If there were 32 mono tracks with associated faders, people would complain about not enough grouping. All the stereo sources, like keyboard, FX, and submixes go on those tracks, and it's considerably easier working with a single fader to control a stereo pair without automation, not to mention a single EQ that works equally on both channels, sends, etc., all equally applied so one doesn't have to worry about adjusting only one side. Once you wrap your head around the fact that you have 12 pairs to work with, and you start thinking like that, you realize how smart the setup really is. In the Production Techniques sticky thread, there are several posts about creating complex submixes using Mixdown mode and re-importing them back into the machine. Also, posts on grouping, by using the stereo tracks. I suggest you use a track sheet (search for them on this forum) and pre-plan all your recordings to take advantage of the stereo tracks.
That being said, there is nothing wrong whatsoever with reverting those tracks to mono for storage, and then resetting them back to stereo later on as you develop your song.