Sorry but I think your issue might either be a Very Isolated one, or Operator Error. :slapfight:FCW seems defective on plenty of WK2's. When is the TSB coming out? Jeep should recognize this and act on it before it becomes a big deal.
One way to diagnose: Test drive 10 JGC under similar circumstances. See which ones warn you and which ones don't of a forward collision warning.
The FCW system on my 2012 Overland works just fine.