There is already flight-simulation software that will run on Linux.
(
Flight Gear).
Flight Gear is open-source, so one can modify the software, and is
quite easy to interface with.
The problem is that most people who want a “home-simulator” want
something that is easy to install and run and has detailed graphics.
That's why most people use MSFS2002/2004, it has the graphics and it
is “easy” to install, but it only runs on windows operating systems.
Besides, the people who build these cockpits probably don't want to
lose time on yet another task, like learning a new operating system.