A cathedral is - among other things - a memorial to its builders. Changing the building is removing that function. Also, sprinklers may destroy more than they protect.
> The state owns all the cathedrals but doesn't insure them, so restoration currently has been reliant on donors,
This may be just me, but I find a rebuild-by-donations societally and spiritually a lot more meaningful than just some insurer and/or state handing over money. See also: Dresdner Frauenkirche [1]. It shows that society itself cares about the building, its history and cultural importance and spirituality.
This is most commonly seen in major disasters where the insurance companies fail and the state steps in.
That being said: as a non-christian German I gave a - to me significant - amount of money to the Notre Dame rebuild. I like the idea of helping build a piece of art that will survive me.
The fire alarm system was acobbled together legacy system, no big surprise in a century old building. Thr number of cathedral fires, or similar fires in other hostorical buildings is negligible. In a sense Notre Dame served as a wake up call.