I do have games where another CIV spreads their religion to a city of mine (that has a Temple) and then the next build on that Holy Site might... be something better than what I can get (say, Cathedral)... so I'll take advantage of that, build it, and then reconvert the city to my religion (if I feel I need to... sometimes I don't).
I think there is some 'fun' in ONE-ONLY aspects of CIV. (like Wonders).
Like... if you want to rush something (evangelizing a valuable apostle to nothing)... you should get the benefit of FIRST CHOICE.
You don't want somebody else being able to get the same thing as you at a later period of the game.
Hard thing with this sort of request is that... you could somehow get it in your game... but if nobody else is doing that quirky mod.... it makes conversations 'feel' a bit frustrating when you want to discuss your 'special settings' game with somebody else. I think you'd find that people don't want to talk about the unique game-setting you play with. (One of my daughters has niche-interests and keeps trying to discuss them with people that don't have those same niche-interests... and she wonders why people get frustrated talking with her... LOL, good kid... but...)
