First of all the JS and the JEM/RG are two completely different animals.
22 frets vs 24 frets, and neck profile of JS resembles more the
Fender strat profile....Joe simply turned Ibanez Radius guitar into more or less his own strat clone.
The Jem/RG has completely different history.......and Steve being more flamboyant as Joe....his guitars have more frooo-frooo.......the inlay, the
monkey grip, the lion claw behind the trem. This all adds to the idea that this guitar is more expensive to make.....and so could carry a higher price tag.
With current CNC and laser cutting equipment this is all bunch of hog wash.......
That whole vine inlay wouldn't cost Ibanez more than $10-$15 per guitar....and they up market the guitar $400-$500.
That's marketing dude!!!
All smoke and mirrors.
And yes if Ibanez and Joe would be little more creative....(read: colors, inlays, etc) the JS wouldn't be out sold by the JEM 10:1.