Of the four Gospels, three of them actually spell out the form to be used in the celebration of Eucharist. Matt. 26:26-28; Mark 14:22-24 and Luke 22:19-20 are the specific verses which command the process of consecrating and distributing the Eucharist. The Gospel of John does not spell it out, but does describe the identifying of Judas as the one who would betray Him in John 13:21-27, which Matthew and Mark also include BEFORE the Eucharist in Matt. 26:21-25 and Mark 14:18-21. Some point to John 13:26-27 for a reference to intinction, but again - according to Matthew and Mark, that "dipping" took place BEFORE the institution of the Eucharist, which John does not record.
When discussing a similar topic with an Orthodox priest (a discussion on leavened v. unleavened bread) he stated " there's a reason the Orthodox do NOT change what we have been commanded to do in the Eucharist." He condescendingly adds, "The west loves novelty, though." It would seem it is the Orthodox who have introduced novelty to the institution of the Sacrament of sacraments, not the west here.
Personally, I do not have a problem with intinction. It is a fine and pious practice of our Eastern brethren.