They clearly know what is not correct with this airplane. Lots of reports relating to the Vnav speed management etc.
I see the same issues on the 757 and that aircraft have been on the market for a while without any attempts to fix this basic Boeing FMS management.
I like realism and the simulation should get the basics correct as a minimum. 
It has potential, but it is far behind when it comes to correct speed management and accurate and precise flight path management.