I wondered if many people wanted to make the game more immersive and realistic. They may be starting to buy external gears like throttle and control column for SP. I recently tried some, and here is how it went:
The joystick and throttle do highly upgrade your "virtual" sense in game, but also highly increases the difficulty. I've been playing SP for over 3 years, and getting used to new gears may be difficult. You may also find it heavy to aim and overall control the plane.
In the end, I am still using my keyboard for SP, and the joystick for some other games (dcs etc.). But if you are too unlikely to install other games, and want the best realism of SimplePlanes, then get one + a shader.