I've used this technique in the past to create a pulsewave by writing a small script that would output the numbers/letters into a text document that you can then import with a nice sweep etc.
It was fun but not anything that can't be easily beaten, such as using a free VST instrument, programming the sound you want, put it in an empty song on row 1, pattern 1, channel 1 and simply render that to a wav file and use that. Much higher quality and more importantly, easier and more options.
Then of course, the only real reason to go for wav files, is if you want backwards compatibility and release a module without vst's necessary, such as in demoscene music.