At the time, there were a lot more JW lifers still alive, who’d cut their teeth on WT oracle Fred Franz’ Cold-War-centric End Times script … my Dad knew it backwards and forwards (and by extension, so did I). A change-up that radical would have alienated too many of ‘em at once, and the Org was way slower to risk that kind of thing back then.
Not to mention that Franz left no protege after he kicked the bucket, and most of the really creative thinkers had been purged out of Bethel during the apostate witch-hunts of the late 70s and early 80s… IMO, it’s doubtful they could’ve come up with a plausible alternative “understanding” even if they’d wanted to.
And, also, I think some of ‘em just liked it… viewing the United Nations as the Wild Beast was something unique to JWs, not to mention useful… since their eschatology didn’t have an actual “Antichrist”-type individual*, the UN could stand in as an actual, tangible villain in their narrative.
*that the rank-and-file might be tempted to spend endless hours trying to identify, the same way thousands of other American fundagelicals have been doing for the past fucking century. 🙄