I've read through the long list of requests that are in your initial post, so I will break it down to you, why most of this wouldn't work, since I have a bit of experience with how development teams work in different environments.
Matchmaking has been a long time issue, it is partly due to lack of players to make matchmaking all the more diverse, currently the only fix for this seems to be the engine update that should allow for the dev team to implement more server-side features and upgrades later down the line.
On another note, the option to quit the missions with enemies in the match has been removed for the exact reason, that too many people kept leaving the matches, often resulting in a very imbalanced, one-sided match. You can abandon missions where you have no oppoisition by simply typing into the chat field /abandonmission, but once opposition arrives, this option no longer works, it is to keep players in a game and give everyone a fair chance of game.
Plus you can get a free perma N-TEC by completing the tutorials, and that is a jack-of-all-trades weapon, I used that for most of the time and I kept killing players who had JMB legendaries, Nanos, etc... Every weapon has its own advantage and disadvantage.
Modeling a car from reference or not takes a very long time for it to be good quality at least, not to mention the body kits that would come with it, then all the wheel colliders, box colliders and rigidbody parameters would have to be individually set up and adjusted/tested to meet realistic expectations. Pulling away resources from more important tasks at hand for making new cars would be a bad business decision overall, QoL updates are usually higher up in the priority list to extend the game's lifespan.
I'm sorry but you are essentially asking the dev team to work on all this and release it for FREE when the game is FREE to play. You are effectively removing their salary and bonus from the time they put in to make all this available. As a consumer you must understand that financial support from the community for a free to play game is their main source of revenue, along sponsoring and other smaller revenue that altogether would not make up for their equivalent expenses rate.
The reason for this is that control mechanics for flying or swimming were never implemented to begin with. The controls (fundamentals of a game) are always worked out during prototyping stages, early development. For this too happen, there would have to be a major overhaul in the game's core mechanics, new controller scripts would have to be developed, as well as major overhaul on maps of water colliders, some water simulation, air drag and different gravity effects on rigidbodies for flying objects, these are all potentially hundreds of hours of work for a small team.
Plus a major overhaul usually means public testing and with an old engine and spaghetti code, that this game was initally founded on, this will result in an infinite list of bugs, adding more hours to get the work done. Again it would be a waste of resources at this point.
Ok so to make this one short, imagine instead asking for a handful of cars, you are now asking for 30 000 thousand new unqiue cars to be modeled and implemented. Level design is by far the most difficult aspect of game development, it takes an immense amount of time to create maps even if it comes to extensions with a more rural terrain.
It is not the focus of this game though. This is a cops vs. crooks shooter game with driveable cars and a state-of-the-art customization option. The literal point of this game is to look cool while bringing criminals to justice or causing chaos. This was emphasized in all the trailers at the time of release, re-release.
Hence why it is called social district. If you have moved prefabs of customization kiosks into tattoo parlors, clothes shops, car shops, etc... the action instances that are meant for PvP battle would be filled with AFK or idling players who would unnecessarily bloat the instances resulting in longer matchmaking queues, less action, because an action district can only handle 80 players at a time. Why, do you ask? Because there is a lot more going on in action districts, gun-shots, windows breaking, explosions and so on, all of this the server needs to compile and run quickly to make sure the latency stays low.
This isn't a bad idea tho, I would say this is so far the only credible idea I would actually be happy to see in the game. Design some interiors that players can buy, your equipped graffiti shows up on a feature wall in your house and you can invite up to 7 players into your house for a party. These would be invite-only instances separate from social and action districts and it wouldn't show up in the instance selection screen. You get an invite through the mail kiosk where you can accept it and it will automatically put you into that invited private instance. Players can access their apartment from basically the district quick join tab.
1. Joker mystery boxes aren't free, the economy of the game would start declining rapidly. Other options would need trackers and given how control scripts work in the game, that might not even be possible at the moment.
2. There are places of interests already. Mostly the statues you can see placed all around the districts.
3. If you mean PvE jobs, no one would bother with the PvP aspect, further diminishing the matchmaking that is currently there.
4. We already had those, not sure why they were removed.
Again, this will require overhaul in the core controls for cars that would take a long time and would be very difficult, plus the bugfixes might require even more work afterwards. CONCLUSION/TL;DR: I'm not saying that these are bad suggestions, all suggestions are in some way good, but they just cannot be executed in the foreseeable future, for the fact that the foundation of this game (the engine it's built in and the code) is proprietary, making changes to the core mechanics extremely difficult, they were not designed to be expandable, modular or plug and play. The only way most or all of these changes could be made is if the company decided to make a sequel to this game and build it anew entirely from scratch in a new engine (probs Unreal 4) with better optimized, more modular code.
But this is probably not gonna happen, or at least I don't think so, because LO might not have the resources to start developing an entirely new game.