The idea of another artist box set makes me want to fall asleep. Like being at a tedious dinner party with Dr Banner, waiting for the Incredible Hulk to turn up and slap on some vinyl.
I get your point but I think it works both ways, in all the artist box sets I have, there are always (at least) a few records that don't get played. The collector in me gets excited for completeness, the accountant in me gets excited if it works out cheaper per record, and I do love the nice boxes, but I'd generally be better off buying individual records. I rarely love all the records an artist makes. Same for a label. But, a box set can give an insight into a label, or artist.
What a label can do is put a different focus on production and recording. The Blue Note example is easiest from a label & artist point of view as well. So many of the artists played on each others records. You had consistency in production with RVG. Wolf & Lion gave the artists freedom to experiment, money to practice and encouraged them to write their own songs, so the label did make a big difference.
I think CTI where known for bringing in strings in their jazz releases in the early 70's, giving a distinct sound. I'm sure there are lot's of other inters testing labels out their for other reasons, but first and foremost, if the selection was of some great albums I would probably buy it regardless of artist or label focus.
@TCell mentioned Screamadelica, that was heavily influenced by the rave scene (written mostly when the band would come in after raves high on E), and the production from Andrew Weatherall. I wonder if an Andrew Weatherall box set would be more interesting than a Primal Scream one?
I would love a copy of Nowhere on vinyl, though.