These are practise DJ sets!!! Often times I am learning new tracks, at the same time experimenting with different combos and transitions. Normally, 'official DJ sets' are free from mistakes, with a perfectly curated tracklist. But they can sound flat and boring.
These mixes are presented with 'warts and all'. And IMO, they have a vibrancy that can't be captured in a rehearsed 'official' mix.