Some faces, expressions or gestures are VERY cute. (like upturned eyes). So it works like a powerful boost to the usual erotic elements. But that may be literally any concept related to childishness. That's just the power of MOË.

>>7041
>>7043
That's very moë, childish, innocent faces.

But yet again, just like with the real counterpart, I feel this is a dangerous path, and it's better to separate watching cuteness and the faps.