Air travel is about speed and functionality. Getting into Paris from the north is a pain and Beauvais is one of Ryanair's least functional in so far as it may not be the furthest point of landing from the supposed destination city but it is one of the longest journey times.
philbky,
Have to agree. If you have a cancelled flight ex BVA as happened before on a flight to Shannon, you will quickly find there are no hotels around it and the trip back into Paris is not short. I don't appreciate the distance between BVA and Paris on a coach, for that reason, I see Dublin as a much better option for a passenger who would ordinarily use Shannon. Cork of course has CDG, that could be convenient for some depending on their location.
Perhaps like in the 90's there could be a 1/2 times weekly flight reinstated to CDG or even Orly. Would Transavia consider that, maybe.