If cortana cannot be used to interface/control apps on a windows 10 computer it has no place either at home or in the enterprise.
To clarify Cortana should be able, as the first draft was, to start an application passing parameters.
That is what it used to do when you told it to play a mp3 file.
It wasn't until much later that Iheartradio and spotify came into the equation and local music playing was lost.
Cortana should be able to open word with word documents, excel with excel documents and either media player, groove or movies/tv with media documents (playlists or other multimedia files).
The developers have blinders on and are completely missing the mark on this, just as windows as a service has completely missed its mark.
Even settings are not the same on two comparable workstations because windows builds the settings based on the hardware it finds and it seldom does it correctly. Heaven help location services and maps for instance.
Were I still in IT and not retired windows would not be my operating system of choice.