I think the Holy See will continue to leave the matter of processing-up during communion for a blessing to local bishops. If the Church ever did try to prohibit this practice I would be it would include language that said something like “…in those regions where this is a beloved and time-honored tradition the ultimate decision will continue to rest with the local ordinary” or something along those lines.
Like it or not, the process of processing up to the front of the church and receiving a blessing from a bishop, priest or deacon has a terrifically strong and positive impact on a great many people. The downside? Negligible.
With all due respect, you remind me of a former member of CAF who kept insisting that this practice was alright, down to the point of digging up an innocuous YouTube telecast that purported to say that the former prefect for the Congregation for Divine Worship and the Discipline of the Sacraments, Francis Cardinal Arinze, did not see a problem with it.
The irony is that this letter, which bears a protocol number and is published in the most recent issue of Notitiae, the official publication for the CDWDS and written before Cardinal Arinze retired, states the very opposite. The practice is ilicit, for the time being. Given the new administration heading up this particular curial office and the new prefect’s strong push towards maintaining tradition, this ruling will probably still stand.
No one, not the celebrant, not even a bishop, has the right to invent a ritual and insert it into the Holy Sacrifice of the Mass. The only way that any adaptation can be made to the GIRM is that a national episcopal conference petition the Holy See for the necessary recognitio. So far, the USCCB has not made such a petition. Had it done so, it would have appeared as part of the adaptations listed in the GIRM.
Furthermore, this kind of practice only yields confusion among the faithful because it creats a false illusion of inclusivity. The invitation that the celebrant makes to the faithful before the reception of Holy Communion clearly states that the faithful, worthily disposed, are invited to receive Our Lord, not a blessing. The letter from the CDWDS makes that clear.
There is no provision for this in any of the authoritative documents of the Holy See. In fact, the Constitution on Sacred Liturgy, which has not been abrogated, clearly states that no one, not even the celebrant, has the right to add anything to the Holy Sacrifice of the Mass. This includes imparting a blessing in lieu of distributing Holy Communion.