Well, in off-roading, with the transfer case in 4-LO, both the Rubicon and H3 will out-torque the FJ easily, esp. at low RPMs.
But, i do agree with you...i wish that Jeep could have found some way to modernized the old inline 6. But, i think that the engine was at the end of it's life. Problem with the 4.0 was that it was terribly inefficient (piss poor fuel economy), bad on environment (relatively bad emissions), and terrible on the highway. Thus, Jeep had to do something. And the closest thing to it is the 3.8L V6 in the minivans. I would not worry too much...a diesel is on it's way in a 2-3 years.