Realistic wings (Suggested by @alexchub1)

Some realistically shaped wings with a flaps control surface. There would be 2 types of flaps, as seen here

I'm going to add on to his idea by saying we should be able to change the wing cross-section and be able to also change the wings thiccness. Also make an option to add flap tracks as a part of the wing, as well as multiple slotted flaps, each slot will be able to go to a different angle.

Flap tracks:

Better water physics

The water physics are absolute garbage. All a boat rudder does is tilt the boat with almost no turn. Seaplanes can't turn in water either. An update to fix this and the ability to bring the camera underwater with accurate lighting effects would be awesome.

Bigger bombs

1,000 lb bomb and 2,000 lb bomb. Also a 20,000 ton MOAB style bomb that is inside a dropping container. The bomb falls out of the container when container activates parachute using preset time limits.

Extreme weather

Then we can fly through hurricanes and nuke them as well. Also includes tsunamis so you better hope your plane is buoyant. Also will generate random thunderstorms with erratic and strong winds with rain effects for harder approaches.
As well as these, there would be a cloud ceiling, so you can actually fly into and above the clouds.

Better high altitude render distance

So you can see more at a high altitude, would increase realism.

My suggestions for new islands

~Sorta like what BaconEggs said, we need an archipelago with multiple small islands, some with their own small airports.

~Also, an island about 5 times larger than Maywar (WITH LESS MOVING PARTS (WINDMILLS)). Add a city instead of a wind farm. The heart of the city would have an international airport with multiple crossing runways. Some approaches will be over hills and have sharp turns before landing, while other approaches will be direct over a river, over a highway, and over some buildings. This island would still be high processing and it would unfortunately not be available on mobile.

~Also, PlanesOfOld suggested a grass aerodrome.

Radar

Would allow airports with towers (Yeager, Bandit) to have radars, which allows ATC communication with an aircraft. An aircraft can also see the surrounding airspace using a small radar overlay in the bottom left corner of the screen, but only if the aircraft used the radar dish part.

Bring back the dummy part

Self-explanatory.

Better paint

So we can paint blocks without adding more parts. Would include a letter typing tool and a brush/pencil.

Refuelling

Adding fuel trucks and fuel parking spots at SOME airports, as well as requiring a cockpit AND a fuel cap part on a design.

The ability to twist fuselage pieces.

Then we can make better cross-sections and do other cool things by having each end of a fuselage block at a different angle, twisting the fuselage. Great for things that are impossible to do with normal fuselages, and can help to reduce part count on some builds. Maximum twist value in any direction would be 360 degrees.

Comment if you agree, and if you upvote more people will see it. Not like I'm desperately asking for upvotes or anything....... :/