I bought a replacement shellholder from Lyman that allows use of standard shellholders. It isn't spring retained, so you still have to use the set-screw, but there you are. If Lyman had done snap-in spring retention, would likely be using the press more often.
Something about the float you get with the spring tension versus hardmounted using set screw. Want that float so brass concentricity isn't compromised... Not like the springs are any big deal to make, could adapt it pretty easy I'm sure. Just never motivated to do so.