I don’t think 6 had religion or a bunch of stuff originally, it had less content than 5 at launch (forget the civs, just the mechanics). That was fixed in the first major update.
I’d expect a year or 2 before we can start seeing 7 become the full game it needs to get to to pass 6.
I stand corrected, must be thinking of civ 5… Or World of Goo…