I think with Blackhawk Archives like Shazam! Family Archives it's a combination of the sales on those volumes and the cost of doing the restoration. Given that Reed Crandall and Mac Raboy's art is so fine--restoring that art, to a level where it respects the original work, probably took a lot of time and talent, which probably ended up costing DC a lot of money--plus they had to find the original comics to use for source material. I expect it's the same for Doll Man, Black Condor, The Ray, and others (with Crandall and Lou Fine art).

But, of course, that's exactly why we want them.

At least with The Spirit, they had the files from Will Eisner, so the restoration cost was greatly reduced.