That’s tough, but a lot more options and flexibility in the mission parameters for starters.
The missions list should be a tabulated job board with more info. Departure, arrival, mileage, runway lengths, duration, start time… sortable columns with filters. There should be dozens of choices with large variety.
Goal oriented missions: Not micromanaged details. Get the cargo to the destination, don’t enforce hold short lines. flight plans, and diversions. The sim should be hands off instead of holding your hand. I should be able to stop enroute for weather, maintenance, or fuel. That’s an automatic mission failure right now.
Continuity: Your airplane should be where you left it, how you left it. Right now, it’s teleported to the mission start in a default parking spot, in a default cold and dark state. If you want to have an employee ferry it for you, great. But I should be able to do all the tasks too. Like, stopping at the pumps for fuel, and taxiing up to the maintenance hangar. You should have the same copilots in Freelance. Right now, you get a new copilot every time. Talk about high turn over rate.
Progression: Not just levels and money, but the missions themselves. Long multi-leg missions should be a thing. Long start and end points that follow a path should be a thing where you pick and plan the legs. Imagine running cargo or doing a ferry flights along the entire western coast of the Americas. Round the world airline transport. A pinboard that shows you where you’ve been with mission types that have the goal of always going someplace new and going everywhere.
No recycled/reused stuff: The NPCs say the same things over and over. AI can be really cringe, but I feel like it could be used here to say something unique. And if that can’t be a thing, maybe they just shouldn’t talk. Recycled details in the mission, combined with the strict parameters, make you feel like you’re playing the exact same mission over and over again. That’s the spell that needs to be broken. It’s a tough problem, but some creativity and ingenuity in making a flexible system is key.