It’s perfectly reasonable to release the BBC sessions since they were broadcast and not outtakes, like what the Rolling Scones did recently with a couple of their albums from the 1970s (Some Gals and Exit on Main Drive), half-secretly improving on the outtakes and completing some of unfinished stuff from the time. (Those Jagger vocals ain’t from the 1970s, dude!)
Well the other stuff (like the full Chess Records’ Stones sessions) have come out of late but as high quality boots.
And the “copyright free” recordings are producing some extensive “greatest hits” (of an artist, label, or era) CDs.
They aren’t that high dollar at Half Price Books (often $6.99 for a two-CD set, maybe $17.99 for a 4 disc/100 track CD set with extensive booklet.