I'm really, really confused as to why people are talking about altruism or socialism here.
Some 80% of the new content in 1.6 is exclusive to muslim rulers - sure, it might exist in the game files of people who didn't pay for Swords of Islam, but the AI having to fret about decadence doesn't really matter much to Christian rulers, beyond maybe making the AI a bit more aggressive when they have stray dynasty members laying about.
It's less like buying three loaves of bread and giving away two, and more like buying three loaves of bread and giving away betamax tapes. Sure, you're giving people free stuff, but does it really matter to you if it isn't incentivizing free riding?