Don't you think that if it was "super easy" it would have been added right away? Or do you work as a dev and know how it's done?
There are very different mechanics in play whether you play with a mouse/kb, a gamepad or a stick.
The old space sims (X-wing, Tiefighter, X-Wing vs Tiefighter, X-wing Alliance) all required a joystick to play. It was hella fun, and I still play them with my 20 years old MS Sidewinder pro stick, but it was definitely a problem for Lucasarts that they released a game that required a quite expensive peripheral in order to play.
It's all about making the game accessible.
And - don't get me wrong - I want HOTAS-support too! - But as a dev I know that things aren't so easy.