Most of the aircraft in this game aren't significantly worse than whats available in the 2000's from a fuel burn perspective. The real quantum leap is from the jet age originals to this second generation. I think people get frustrated with the lack of range and the lack of an "easy" plane type choice since manufacturers weren't as boring back then.
Its actually quite hard in this scenario and Jet Age to pick the right plane for your base and intended missions. If you chose the wrong plane type or utilize it incorrectly, you won't do well. In a 2000 era game, most will choose 737 or A320 and it will fly every mission they want just fine. There's no thought as far as the capabilities and advantages/disadvantages of each plane.
For example, if I decided to roll with DC-9's in LAX I would be lucky to be able to utilize a couple dozen of them before running out of options of cities with demand (assuming no tech stops). However, chosing the DC-9 in Atlanta would give you the ability to have hundreds of them in service due to the east coast being more densly populated than the left.