I totally agree with you. Jazz CDs go in and out of print so fast, compared to pop and such that I just don't see the point to this. Plus, as you say, there are plenty of avenues for tracking down OOP stuff.
As for the Mosaics, I could see their point if they were limited to the point that they sold out in a matter of months, but calling a product "limited" that takes three or four years to sell out is just a marketing tool, not an actual limit...