I didn’t say traditional J2 targets can’t be reached from the Carolines. Naval units (and therefore transports) at New Guinea can’t reach Borneo, Sumatra, Malaya, and Kwangtung all traditional J2 targets.
Carolines can’t reach Borneo, Sumatra, and Malaya either.
Both of these distances for targets doesn’t really matter because other ships and transports have to be staged in SZ36 anyways. Ships at Carolines hit the areas within reach and ships at SZ36 and SZ20 go to the areas for landings that Carolines stuff can’t reach.
Looking at the map right now, I can’t grasp how New Guinea presents a greater threat than staging a fleet at the Carolines. Also, more stuff can get to the Carolines on turn 1. Aircraft carriers can be moved to sea zone 46 anyways to pick up aircraft if they hit ships at SZ62 anyways. But just sitting at SZ46 takes away the flexibility of the naval base at the Carolines. With the naval base, the ships are not out of position and could go back to reinforce SZ6 if needed.