OGG also has a 375.000 pound maximum takeoff weight restriction, back when the airlines operated the DC-10/L-1011 aircraft, they would have been to heavy for the runway if they had to fly OGG
to the west coast, so they had to hop over to HNL
for more fuel. I did this a few times out of OGG
With the 767-300 they can carry enough fuel to as far as ORD
and still meet the weight restriction with a full passenger load.
The 767-300 is a long range airplane that can carry fuel enough for 13+ hours of flight, so the fuel load for a seven hour eastbound flight is just over half of the total fuel that can be carried. This translates to less take off weight and less runway needed so they can operate easily and safely out of OGG
's 7000 foot runway all year.
The runway has not been extended beyond 7000 feet and I doubt it will ever be extended under the present governor, the Maui County Government does not want fully loaded 747's landing there. And the current governor of Hawaii is the former mayor of Maui County, and she led the fight against extending the runway at OGG
I also doubt the 767-400 can meet the weight restriction on any flight beyond LAX