Yes, if you could find a spherical bearing of the proper size, you could install them and some spacers to get the same effect.
For example, here's a company that can supply spherical bearings for all suspension joints on a Miata. The picture shows tubular components, but they will also do the same thing for stock components.
Miata Rear Tubular Chromoly Control Arms set - $800.00 : Weekend-Racer - Auto Racing Safety Equipment, Auto Racing Gear, Auto Racing Helmets, Auto Racing Suits, We're amateur racers just like you.
The advantage to rod ends is their adjustability. You can easily put the ball joint anywhere you want. I can get 8* of caster without running out of threaded rod in the upper control arms.