project theora: why not xvid?

I am not very much into the details of open source and licencing etc.. So the answer to this question might very well be an ovious one. Can so . please explain why xiph implements an inferior codec like vp3 into project theora. is it because xvid creates mpeg4 streams and is hence affected in some way by the mpeg4 license?

Here are the mpeg-4 licensing fees made by our "friend" on2:

Spot on. Basically XviD is illegal to use for anything but research, without a license for the MPEG-4 patent pool, and on top of that illegal to distribute (because the patents invalidate the GPL, so you dont have a license to distribute to XviD). So its pretty much useless for law abiding citizens ;) Xiph always intended their codecs to be patent free, they sponsored the research to be relatively certain Vorbis was. On2 have done simular research for VP3. Together with the licenses for On2's stuff this makes VP3 suitable for a Xiph codec, whereas MPEG-4 clearly is not.