I reject the notion that cosmopolitcan secularism would want to ruin Notre Dame by building some IM Pei-style monstrosity. I really don't know if that trend really has a demographic supporting it beyond architects who want to make a name for themselves.
The government wants it. Macron for one has no respect for France's heritage, and then "Jupiter" wants to leave his mark on history by making a big modification to Notre Dame.
Do you have any evidence for that? You know I'm no fan of FBM, but I don't think it's fair to just assume he has some ridiculous plans for Notre Dame just because he's a he's a megalomaniacal creep (which he is).