And as everyone always states in response to that nonsense: That has never been true of their other games. You can't only play as the UK in Victoria, you can't only play as the Roman Republic in EU:Rome, you aren't prevented from playing an archer on foot in Mount&Blade, etc. It's such an idiotic apologist argument that it is hard for me to believe how it's repeated AD NAUSEAM.
Now what -is- valid is that the description of the game when purchasing it explicitly says that in it's original state you'll only get to play Christian Lords. That's perfectly valid and I agree there's no problem in doing so, but apart from new people who just happened to not read the description the biggest real complaint is how the new policy is out-right hard-coding deliberate restrictions against modding (which Paradox has always had a reputation for being friendly towards) for business reasons. It isn't about our money, it isn't about everyone but you being too stupid to understand that Crusades are Christian (Hint: Sarcasm), do you know what actually is a very real concern? Hard-coding things that are incredibly easy to mod in the other Clausewitz-engine Paradox games for absolutely no engine-limitation reason (As with CK1, where the original engine was more limited), but rather just to implement a new DLC policy.
It's a shock
* because there wasn't any form of alternative implementation, such as mechanic-changes of the DLC themselves containing the lock so you just aren't allowed to use the specific "norse_pagan / finnish_pagan / etc." phrases in modded files and expect it to work and that those are required in the Hardcode to use the religion-specific mechanics unless you own the DLC, it just shut it down. I don't even see how it could combat piracy anyway, since it's not like it (or anything else) would keep pirates out, they'd just have cracked Exes to use it and the paying customers end up with the locked game.
* And despite what gets repeated by a few people, without a single link or quote, it was something deliberately avoided by Paradox to comment upon. Not a single response to anyone during development, just "have faith". That's literally all I've seen on it. Faith is humbug.
At least you can take solace in knowing that your DLC will, with utmost certainty, come long before what I care about (Fleshed out Pagans, or, more precisely, Fleshed out Baltic-pagans (Norse, Suomenusko, Romuva)), since the Northern Crusades don't really count since they aren't killing scary Arabs!
(Copt or Maṣr, out of interest? Guessing Maṣr from calling yourself Mameluke.
)