It would Ruin the game. traffic would be better. it could have a multiplayer mode, though. BUT NOT THE WHOLE GAME MULTIPLAYER!
There are people in the world that want to drive normal in BeamNG, with multipayer it would be impossible because everyone thinks: "LETS SMASH INTO SOMEBODY!!!!!" if you don't believe me, look it up on youtube. For example: ETS 2 Multipayer. Even if it looks normal, there's always somebody trying to smash into everything they see.
Because people don't want to drive normal, dev should cancel their plans of making MP? Because in ETS2MP, admins are very strict with their rules and rammers get a lot of bans. Still, there are rammers, but these are in the minority. I drove for full days in MP servers and didn't got rammed. People crash in real life too. Should manufacturers just stop making cars then?
Everyone wants multiplayer. Everyone has suggested it. Devs want multiplayer. Devs can't do multiplayer because the technology just isn't there. I'm just going to dream here. Imagine how much fun it would be to join a server on grid map and just screw around with 5-10 other people. Or you could join an east coast server and do some races with others.
I honestly don't want online multiplayer, I want splitscreen local multiplayer. The main reason for no multiplayer is our CPUs simply can't handle it. Try going to grid map and spawning 10 cars. Your FPS is going to go into single digits unless you have a high, HIGH end rig. Also, you would need to receive 2000 frames per second worth of data from everyone on the server, and send your physics data at the same time. I suppose that the server could just transfer location data and let all the physics be client side, but that opens up a whole NEW can of worms. I feel like splitscreen local multiplayer is doable though.