I agree with @orb and even more so with @Tornadic_Outlaw.
Right now, my biggest concern is how to get as many planes as possible to the gates without 4+ runways.
Because it looks ridiculous and is unrealistic.
Let me paint a colourful picture of what I hoped ACEO to be in comparison to “the other game” in the genre:
A game, where your terminal design requires you at a certain point to have seperation between arrival and depature zones, from the gate to the baggage claim area, maybe even gates where you can decide which floor you want arrivals and depatures to be routed through.
Passengers arriving walk through the specific arrival walkwas, seperated from depature by walls or on different floors, making their way through immigration (intl. flights), picking up their luggage and leaving through a customs gate. From thereon, they rent a car, take a taxi or public transport or walk to their car/get picked up.
Depature works in a similar fashion. Passangers arrive by any means of transport and walk towards check-in. They then pass through security and immigration (intl. flights) to walk through the terminal area where shops, pharmacies, bathrooms and restaurants are located. By lifts, stairs or escalators they can reach airline lounges a floor above, where one may find a few offices too.
The thing that really makes a seperate terminal or area of such necessary, is immigration.
Even though centralized security is rare, it is not really a problem.
Most airport services, offices and other things like firefighters, airport hospital vet. etc. would be located on ground level, including walkways for maintenance. with staircases to the public area and doors that require security clearance (i.e. staff only area).
Different levels of streets would allow for seperate traffic flow for depature drop-off and arrival pick-up as well as self-made car parks.
I explain it in such detail to give you an idea what got me hoping for this game back in the days when EA was released and I got it right away. I already left out cargo terminals or airline services (repair, maintenance).
In comparison to SimAirport (I think many of us own both games), I always saw AirportCEO as the more complex version and SimAirport as the PrisonArchitect.
Many reviews have had a similar impression, if you go back and search for it.
What I am trying to say is, that an airport is complex and if you want to mimic anything remotely close to an airport (and most of it is planning, not operating one), it gets complex, it is a challenge and that is exactly what I love about it.
Otherwise, I can go back to PrisonArchitect. And even that went forward with becoming more complex over time.
Complexity should not scare the devs, because I doubt that it scares away any players, it actually lures us and makes the experience rewarding.
Simplicity feels more limiting than liberating.
P.S. I feel like this sounds quite harsh - it should not. I do enjoy the game, especially early and mid-game. Moreover, the development over the last years was nothing short of amazing!
It should be a productive criticism