I think I would be fine with a modern roof that respected and blended in to the Gothic style. But the designs I saw were all frankensteins of the elegant Gothic

I think I would be fine with a modern roof that respected and blended in to the Gothic style. But the designs I saw were all frankensteins of the elegant Gothic original and a completely unrelated style. The stained glass idea was interesting, but it and several other designs drew the eye's focus to the roof, rather than the main body of the building. It's sadly out of fashion, but I definitely think that architecture needs to blend in to its surroundings, which in the case of the roof is the rest of the building. (Of course, I'm not French, so my opinion has no weight in the matter)