I just noticed that original Witcher game uses Ogg Vorbis for soundtrack, so I figured that engine supports it. CDPR probably preferred Vorbis for better technology, and also since it's an open codec (otherwise they'd be probably messing with mp3 licensing which is pointless, when there are better and free codecs around).
In everyday use I prefer Ogg (Ogg is really a container, the codec itself is called Vorbis) - if I transcode a CD let's say to audio files, I always use Ogg Vorbis for it. It has several benefits over mp3:
1. It's open codec (mp3 is closed) - no patents attached. So you can use it for Web audio, which you can't do with mp3 (i.e. <audio> tag).
2. It has better compression for the same quality and smarter algorithm for decoding, so it saves space, processing power and energy consumption on decompression, consider it more "green" if you like. Most don't pay attention to energy factor, but it's there (it becomes more relevant to those who host media content, consider YouTube for example).
3. Vorbis is just a next generation audio codec, comparing to older generation and inferior mp3. So you just use better technology.
Even next in the line is Opus (state of art and also open codec), but its really new, and lacks wider adoption. Vorbis on the other hand is around for a long time already, and gained enough adoption, that many digital players support it now:
You can read about Vorbis tagging here: https://en.wikipedia.../Vorbis_comment
Most normal players and audio processing software support such tagging already.