Robert Taft addresses it himself, actually. Courtesy of Dan Nichols.
The Roman Church's current sacramental discipline regarding first communion (and chrismation), denying children communion until the age of seven, is the product the breakdown in Latin theology as it became isolated from its Greek predecessor.
The scholarly argument against the practice of the Roman Church is substantial. Nevertheless, though this practice was born from a decline in theology, it is the source of many sentimental religious occasions in the Roman Church and it seems unlikely there would be much desire to change it.
Again, for the record, I side with the Orthodox on this issue.