Well I wouldn't say places like India or Russia or Africa aren't really needed in a game made around the Crusades. It's an odd, mostly forgotten but valid part of strategic game design. Point of Interest then their Neighbors. So that way you don't have the game set up necessarily so it's nothing but an all or nothing slugfest between two sides necessarily. Islamic nations can't just wholly ignore everything to focus on the Christian World because there is a potential threat in the "Backwater" as it were. Same deal with Christians unable to drop everything to deal with Islam. Orthodoxy throws everything at reclaiming Antioch which gives an opportunity for the likes of opportunistic pagan slavs to take a slice out of Orthodoxy during the war, etc.
Though China does have a point of being a bit too far removed. As China would influence the likes of parts of the map that mostly already serve just as fodder for Mongolians or a potential spoiler themselves.
Though I did from day 1 wonder if they would expand the map eastward because of how the kind of drew it. The Eastern edge looks like it was something they were planning on tack on extra to compared to the West or Southern.
Now all this said? In particular I could see a good reason to add a sort of Far East area to the map. And that would be the far older than the time frame of the game, and still used throughout the entire point of the game's time frame, silk road trading network which was key towards a lot of cultural and technological development in both regions.
But that's the thing. It would (and probably should) be part of something quite major. Including trade as something other than a Harbor building in a coastal province providing some development growth (which is basically the only presence of "trade" and economics as a concept I see in game outside of just taxation of the land ala Manor Houses and Fortification Tolls). Perhaps even including more diplomatic means between the courts of characters as during that period you had things like Byzantium establishing embassies in China, and Chinese figures who were trying to secure alliances with nations as far away as England and France.
It could develop into something of an interesting set up of having basically four big power centers dominating the map in the early game of Byzantium, the Caliphate, Scandinavia (due to its impact with Viking Adventures and such dominating a lot of Western European play early on), and China, with the areas between and around as interesting levers. And those four areas would have interesting knock on effects that could be involved in the game. From the evolution of Baghdad to its importance as the dominant city on the Silk Road in the game's time frame (and making some of the otherwise less desirable areas there into strategic and prestigious assets).
But it's also be a big overhaul rather than just something really easily added without much thought or care. Not that I can't see it happening. But I imagine kind of has some comments here have posted there'd be riots over such a work compared to things most would list as higher priority like more development of Byzantium. Which is a very fair priority and makes a lot of sense.
In terms however of what I'm getting from developer messages however their biggest concerns design wise seem to be two things. One is kneecapping players from rapid expansion, and the other is trying to make internal conflict and realm management more interesting. Which are kind of related but it does seem to be two different impulses. Now adding more map isn't going to really kneecap expansionism in the game. But I could see how adding the concept of trade with such a distant, but relevant power, the economic, cultural, and scientific gains from it, the impact it had on societies at the time, as an interesting part of that "Make internal management more interesting" side of life. Because in practical terms they don't want a situation where the Seljuks can just go march to China and take it over. But they might want a reason why China is relevant to the Seljuks and their own story over the generations as it was part of the history at the time and is something else to do but World Conquest.
