It would be nice for me to get individual master tracks for sampling purposes. I would pay for access too, but I've never even seen that as an option.
There are some fascinating isolated tracks out there, but I wonder if knowing that stems will get released will push things in the studio even deeper into the territory that every recorded note must be perfect. Making a record already produces a lot of self conscious anxiety that affects your decision making, so knowing that people will also be listening to and analyzing your individual tracks is even worse!