Two points here:
a) even if your product is free, you presumably want people to use your stuff. That means you should make it easy to use your files for as wide an audience as possible. My point still stands.
b) when we say "uncompressed", we mean"losslessly compressed". Putting your stuff in a zip file is fine.
c) a gigabyte is a lot of music - even in an uncompressed format, you can fit about an hour of CD quality audio in there.
(My points were losslessly compressed into 66% of their original size. I did not miscount or make a typo.)