If I'm not mistaken, it's not that MP3's won't work with GE, it's that MP3's are not supported because the people who hold the patent, charges anyone who uses it commercially. Makslane would have to pay if he included support for it in GE. If anyone used GE to make games for sale, they would also have to pay.
I notice ogg vorbis format is similar and good quality compared to MP3. It would be helpful if GE will support .ogg file for use as sounds, besides how it's used now as music. Do any of the other file formats for sounds compress better than .wav files? I desire small file sizes where possible.