you meant X-Plane, didn't you ;) but I agree. In this discussion I always read the word "complicated" / "uncomplicated" aircraft... Isn't this a huge missunderstanding? PMDG has experience building manuals for real airplanes with hundreds, no, thousands of pages. THAT is complicated, because lifes could depend on the quality and precission of such manual.
Taking this into consideration when building a plane for a sim, it might become true, that ALL planes are complicated.
Assuming a development on a 777 for example, it might seem "complicated", wich is definitely not ! This plane exists already for FSX.
Visual Model and Textures? might be ready for usage with some modifications (?)
FMS? Where is the problem? the complete logic exists in written Code !
3D Cockpit? Eventually the same thing. Modify the existing material, if at all
Flight Model? That is the only point I can see as "complicated", since it has do be started from scratch. But this applies to ANY plane