Of course there's no excuse for not supporting WAV files, but why on earth would you want to use this format? It's lossless, sure, but it also won't store meta data like artwork and album tags which makes it virtually impossible to manage/organize music (except if your really comfortable with working in folders only).
You should seriously consider converting your WAVs to FLAC or ALAC since both are still lossless, but support meta data. Of course, neither of those will be playable on WP8 though - which is again inexcusable, but you could also go with WMA lossless which isn't very well supported outside the Microsoft ecosystem but should work flawlessly on WP8 and WIndows in general. That way you'd have it all: Lossless quality, proper meta data and embedded artwork (you need to fix that on your own though as WAVs come without any of of that) and support on your WP8 device.