B Ed,
Because. There are a lot of folks out there who have 45s. They wan t them to be more comfortable to shoot. They aren't necessarily "GAMERS" and they aren't necessarily chasing "Gamer Loads."
For a less "intense" experience, something easier on the wrist, the 45 Colt is a very inefficient cartridge. Getting a good burn at reduced load levels can be difficult at best. The 45 CS allows a lighter load in a more efficient configuration. Instead of messing with tons of "fillers" a smaller case just makes more sense.
Now that Starline is selling it direct, it's not "Pricy" nor "hard to get" special brass. Buy it like any other brass. There is a marked difference in length between 45 Schofield and 45 Spl. Just go to your supply of brass and set a 45 ACP next to a Schofield. The difference will become painfully obvious. Nanny Nanny Poo Poo!!