The focus of the game is surely medieval, feudal, christian western Europe. Expanding the map to encompass India, China, Africa, the Steppes and so on seems fine on the surface as these place obviously existed during the timeline, and well, moar is moar right?
But these are not areas which greatly impacted medieval, feudal, christian western Europe so at best theyre surplus, and at worst they could lead to jarring results that break immersion in the medieval, feudal, christian western European setting.
India and China and even the Arab world were vastly different places to medieval, feudal, christian western Europe - Is an Indian ruler truly going to be embroiled in a contest for authority with the Pope like a ruler of the HRE would be? He is going to have other concerns and other cultural strains that must either be modelled in as much detail as the games focus (unrealistic given time/budget constraints) or some souless cookie cutter events/decisions must be presented in such a way that the situation for a ruler in India is not much different than a King of England.
Id very much rather that PI concentrate on the games focus - medieval, feudal, christian western Europe - and the events and tensions of that era in great detail rather than try to make the "Game of Everything" and be unable to model any particular culture or historical era in any detail. Believe me, Western Europe is a pretty broad canvass in its own way so PI will be walking a tightrope between gameplay concerns and historical accuracy as it stands. All those "Bastard" event chains in CK1 made sense from a really high level overview of Europe - however they were meaningless in the point of view of peripheral European cultures who didnt have a concept of "Bastard".
I rather those complexities were better modelled than sacrificing them to try to reflect cultures that didnt significantly impact Western Europe until well after the timeline. Quality, not quantity.