Ok, let's ask it this way...
Would you rather rely upon your controller inputs directly affecting the flight of your plane, and have the collision model we have? This is a client-side game where data from your controller directly affects your flight, and your data is passed through the central server to the other players.
Or
Would you rather rely upon your connection to the central server where your inputs are sent to the server before your plane's controls are affected, and have the server determine if two planes collided? This is a server-side game where your plane's flight is determined by whether the server received your control input, and then sends the data to you and the other players.
Personally, I would rather be in direct control of the flight of my plane. I tried a server-side game, and was immediately put off it when my plane continued to fly into the ground because I lost control of it when the sever connection had a hiccup and it failed to see my controller inputs.