I played the first Crusader Kings. I didn't play it a lot, but I played it, and before Crusader Kings II. I held little expectation that the sequel would introduce the option of playing non-christians. However, I maintained Hope.
I realize, the game relies heavily on the feudal system. I realise, the way it handles it, is unique to christendom. I realise, they chose to emphasise this. However, even with those realisations, I did not lose hope of them covering this.
Why? Many reasons.
1# They have an active community now. In the last few years, Paradox Interactive has grown substantially. They have a larger community, and thus pleasing particular demographics of such has more incentive.
2# I had hope that they'd not hard code it, thus there would be potential for it to be handled by the mod community. Paradox Interactive games are famous for their comparatively easy modification. This hope was admittedly dashed when I heard it was hard coded. Maybe they'll change that, maybe they won't I don't know.
3# This is, as far as I know, the only series (of theirs) that covers this time period (maybe theres a few modded exceptions). At least, the only game with a format similar to Crusader Kings (that we love). To leave out the non-christians like this, feels like setting a goal. They're gonna focus on one part, and do it right. however, they have time to flesh out the setting and show multiple sides. It is 'Crusader Kings' I get that, I do. However it is also a period of history and it has room for fleshing out. It has room for expansion.
4# Multiplayer. For a long time, protagonists and antagonists have fought within video games, players have assumed both roles. The faceless AI can have an added threat, an added flavor when a player is in charge. This undoubtably, would enhance the experience of those fighting as Crusader Kings. Players are every bit antagonists to each other as Christian kings, but this can take it a step further.
5# You can technically play pagans without cheating correct? I believe someone verified this before, but I havn't verified it myself, but being a vassal to a lord of another faith, can allow you to be a pagan. If they allowed such a thing to remain in the game why not go all or nothing? You don't want people playing with pagans, yet accessing the same incomplete pagan/islamic experience is there within the play. If you can allow that to happen through player action, why not allow them to grab that by choice at the start? Ofcourse, maybe they've changed that since the demo/beta, I saw it on youtube.
For all those reasons, I maintained hope, and still do, and I think they more then legitimise the hope, even if individual desire alone did not. It is of course, Paradox Interactive, and theres no guarantee, no condition, no valid demand that they implement this. Its their game, its their right to do or not do it. Their right to leave it out, or put in the effort to flesh it out. However, complaining that people on this forum, would have the audacity to want to play a non-catholic faction, in this game, this engine, is ludicrous. They can desire it all they want and theres valid reason to want to play a norse, a tengriist, a sunni, a shia, a whatever.
Edit: Though I also realise on the opposite side there has been good points such as expanding whats there rather then compromising on new additions, and that people should not be so quick to complain that a feature like this wasn't implemented from the start.