It's fair to say that FJ is a simpler in some respects than it's predecessors, but that was by design. We'd done tables with 3 and 4 flippers before and though it was time to try a simpler 2 flipper design. More complex doesn't necessarily mean better of course and we thought a 2 flipper game would be a bit more approachable than what had came before.
As for whether or not these games could be made in real life - I can say that they were certainly all designed so that they could be made for real in theory. But that's not to say that some of the mechanisms would be extremely expensive to make and a nightmare to maintain for real.