Thing is that Marti went the way with least resistance. As for wav-files, one does not need any DLLs or similar to play it (unlike mp3, for example). A similar thing applies for bitmaps: those images are not optimized in any way, the exe doesn't need to "decrypt" the image to find out what's going where, it's fairly intuitive instead (for a computer, at least).
There was once a patcher for LF2 that enabled reading PNG-files. The good thing is: your sprite-folder is only 10% of the original size. The bad thing: loading is super-slow (internally, the png's are being converted back to bmp to treat those accordingly). I guess, a similar thing would apply if one enabled non-wav-support for sounds: reading *.xyz, converting to *.wav, and working with that.
The only way to play wma-files is by using the "music"-tag. The downside is, though, that it interrupts any playing background music.
So, I guess you can bury your ideas as they're simply unpractical. Also, DCing-section is, indeed, a bit inadequate.... therefore, --> hex