160kbps ogg is not exactly low quality. Most people can't tell the difference between 160kbps ogg and lossless, nor do they have the equipment when listen to. And with huge amount of data like this, it might be impossible or too expensive or too time consuming for them to archive in lossless quality.

I agree, archiving audio files should be lossless when possible, but that is not a requirement. 160kbps ogg is "good enough".