Hmm, using the ufo-mode "flight" as an arcade-like flying object handling, whyte some free hand to modify the turning and speed characteristics for each such vehicle ... know there was some talk about lighter handling of vehicles. Think too, that the best would be to have the two modes approach, where both - sim and arcade handling would be there and you would just choose witch you want to play.
Not sure if and when Cameni would add that to the engine, you have to understand that for now, the simulation-community is in the main focus for them (think mainly for the people contacting them for potential and going on projects). Doe, im sure the second way comes eventually (arcades will want to have some slice of the engine too).
... Not sure about the possibility of simplifying the JSBSim script, but i think the main flight-physics behind it could have some loop-holes for making a less realistically behaving plane. Maybe even a way to make both - sim grade and simplified to be choose-able in some way inside the JSBSim script. Doe i have zero experience in that one, so i might be wrong about that possibility. Maybe, when additional forces can be added to the flight-scripting (like the movement forces for ship-handling, or force impulses in the vehicle-script), there could be something build by simply an selectable intensity-variable push-force and the wing/frame lift characteristics.