Just Chipping in here.
I had a discussion (if you can call it that) many years ago with Saga Musix about why not, and he had a very good point. The idea I had was having the format with a synthesizer in it, so you have a small format, and s3m already had this, so why not, right?
Saga pointed out that only a few programs actually support this playback, which are basically trackers, and that the playback is not accurate (yes Saga already mentioned this), but on top of that, and that was the part that just made so much sense that I stopped my quest for this... If you want synthesizer support in your module, just add the VSTi you want and use the IT or MPTM format. Now obviously, I don't want to open old songs, but in OpenMPT you can still open the old s3m files, convert them to IT or MPTM format, and use VSTi's and recreate the sounds they should have in order to "convert" them to a new format.
Alternatively, you could export these songs to wav/mp3 etc and use your favorite music player to play the old files. In best case, scream tracker 3 can export to wave too, which is the native for s3m files, and this can be run through dosbox.