codec development involves real research work

Sure, the money rolled in when MP3 got licensed. What the patent also did, however, is to stifle innovaton – why would you improve on a proprietary codec if you couldn't use it, much less share the work? Also, a lot of video files, in those days, consisted of ~30% audio, uncompressed, because freely-available codecs weren't allowed to support MP3.

Only the LAME people seriously improved the state of the art (they implemented a new psychoacoustic model which improved the quality of the encoded data stream a LOT), and they basically disregarded the whole patent mess and, fortunately, managed to not be sued for it.

I have no idea how much work the Vorbis creators spent on circumventing the MP3 patents, but it's certainly not zero.

And so on.