1.Realistic and complicated aren’t necessarily related.
Study level means that you can basically use the aircraft to train for your type rating and not even the Aerosoft CRJ is study level.
If you simulate normal ops you don’t notice a significant difference between the rather basic Aerosoft and the study level FSLabs A320, except for the much lower performance of the latter.
2.Haven’t tried it myself, but from what I’ve read the FBW A320 appears to have a higher impact on performance than the default A320.
If you adjust your settings you can have a very smooth and immersive flying experience in MSFS even with a subpar PC.
Flying a complex aircraft you will most likely have to lower your settings even further if you want a realistic = smooth flying experience.
3.A default study level airliner doesn’t make sense from a ROI POV for MS, that’s all.
Flying a study level A320 from A to B wouldn’t significantly differ from flying the default A320 from A to B.
You can’t jump into either one without any Airbus knowledge and fly it successfully.
Why should there be any loss of revenue? If the aircraft is too complex, people will simply not fly it.