I think it is wrongheaded to attack meaningful worship because of an outmoded insistence that all worship must conform only to traditional forms. A mass meeting in no way harms the local churches. I don’t see how a Catholic can seriously criticize the Youth Days given the energy and in all probability the salvation for many that they have contributed. I am not Catholic but am friendly to Catholics and would love to see all Christian churches grow both in numbers and in the depth of the commitment of their congregations.
I appreciate your thoughts; but, not being a Catholic, it might be difficult for you to grasp the Holy Father's concern here. Certainly there's nothing wrong with mass meetings of Christians; but, for us, it's a question of what kind of meeting. Given our faith in the Holy Eucharist as the Body, Blood, Soul and Divinity of Jesus Christ himself, the question is whether a mass gathering is the appropriate venue for the Holy Sacrifice, or should something else be done on those occasions. Why not just a Scripture service, or some other devotional activity? Why does it have to be the Holy Sacrifice of the Mass?
In the old days, Masses were never celebrated outside of a consecrated church except under very strictly controled circumstances; and that seems to be what Pope Benedict is trying to appreciate. I found the bit about Jungman's influence in Munich very interesting, as it paved the way for the first "mega-Massses;" and the Holy Father seems to be questioning his reasoning.
In any case, I'm glad that Msgr. Marini has been dispatched in advance to take some control over these celebrations away from the locals and enforce some liturgical decorum.