Q: Why was St. Joseph’s name only inserted in EP 2, 3, and 4, and not the others (realizing that he is already included in the Canon). Is it reasonable to extrapolate that one could include St. Joseph in other Eucharistic Prayers?
A: I’m not sure who knows. The change happened shortly after the election of Pope Francis, so I suspect that someone was working on it before Pope Benedict retired. I can’t imagine that this was the first liturgical issue Francis wanted to present.
I think it’s more likely that whoever promoted it was familiar with the four eucharistic prayers contained in the Order of Mass, but not really with the others.
I don’t think one could extrapolate that it’s therefore fine to include Joseph’s name in the other prayers. If that were the intent, the directive would have said so.
Actually, I was probably the only guy not happy with adding Joseph to three more prayers. Joseph may smite me for that opinion, but the compilers of the post-Vatican II missal made a deliberate effort to diminish the number of saints mentioned in the eucharistic prayers partly for historical purposes, partly from ecumenical sensitivity. I covered this in my book At the Supper of the Lamb.
Saints are wonderful, and especially Joseph. But the eucharistic prayer is primarily about other matters. Saints find a most expressive place in the collects.