But why? A 2006 study on the “effect of gazing at the camera during a video link” has shown that retention of information is negatively impacted when the listener does not feel that the speaker is looking into his eyes (even if he knows that the speaker would, in fact, only be looking into a camera lens): “perception of gaze aversion over a video link (a consequence of...not looking into the camera) has a negative impact on information recall.” But more than “information recall” is lost.
Against traditional metaphysics, Emmanuel Levinas considers the face-to-face encounter to be the ground of ethics. It is in this encounter where each subject achieves the recognition of the other. Upon recognizing the other, I am beholden to him – the face, in its infinite vulnerability and significance, demands my obligation, just as a guest is owed hospitality. Eye contact is, in a sense, the active ingredient of the face-to-face encounter:
This gaze that supplicates and demands, that can supplicate only because it demands, deprived of everything because entitled to everything, and which one recognizes in giving… this gaze is precisely the epiphany of the face as a face. The nakedness [nudité] of the face is destituteness [dénûment]. To recognize the Other is to recognize a hunger. To recognize the Other is to give. 
In a face-to-face encounter without eye contact – a simulated face-to-face – the face is emptied of its significance. The “hunger” of the other goes unrecognized. This is a casualty of the Skype gaze. The question “who?” – the question which the face, without speech, both answers and asks – goes unanswered. Here, anonymity begins to creep into the primal scene of accountability, and my obligation to the other, to the face on the other side of the video link, is thrown into question. The ethics that follow from this impoverished encounter are destabilized.