The spring seat is actually comfy, except for the annoying problem noted, because the leather conforms to the shape of your butt -- probably even bony ones, and the springs do the work that padding does less well.
Most bicycle seats are padded with some sponge or something, that feels like it would be pretty good when you press your fingers into it, but, of course, it's not your fingers that press down with such little force when you ride. The physics are different.
Sponge compresses, and you have a hard plastic/fiberglass/whatever support structure pressing on your bony butt.
Leather flexes to spread it's support over the contact surface, and the springs provide for even and distributed "give" with the bumps.
With a regular seat? The pressure points take the hit.
I think the sprung seat is the better concept, and a seat material that can conform, like leather, is ideal. You may note that that sprung seat has no "frame" around which the leather is wrapped. It is suspended between the 3 springs...a bit like a hammock.