There are plenty of good reasons for not adding support to additional codecs without good reason to.
1) Different (and confusing) compatibility depending on the exact model of your product.
2) Need to keep support indefinitely otherwise you cut off previously supported content in people's libraries. People get far more annoyed when you take something away that if you never enabled it.
3) If you have Apple's scale and people will encode to your format anyway a narrow minimal range of formats supported will reduce debugging and handling of edge cases and file types.
Free codecs are a niche concern, almost all users get them [edit: by "them" I meant AAC/AVC/MPEG4] free from their OS provider and in the trickier cases like Linux there are plenty of sources for open source codecs that you can obtain as packages for nearly every distro. AFAIK there has never been any legal action to try to prevent these packages being distributed. So in practice using Free codecs is an ideological decision in most cases and very few people care (I used to but I got over it, the AVC and AAC licenses really aren't that bad if you read them).