This doesn't make sense to me either. There's already an air tight seal from the rubber cylinder with the little brass ring in it that attaches above the coil and meets the underside of the silver cap that caps off the tank. The air shaft hole can't be made any smaller than that. The tip has an o ring, so there should be no airness.
Someone said the 'easter egg' is used for dripping, so it doesn't spit it back in your mouth or something.
I think it's a way for Vivi to narrow down the air flow for a more condensed stream of vapor while still retaining the large opening if one wants to drip. IOW, adding the little rubber peice is cheaper than manufacturing the inside of the drip tip to be tapered and curved, so they just cut it straight and add the 'egg' for a more condensed stream of vapor.
My vivi's fine. I only was concerned because I absolutely hate these gigantic hard plastic drip tips on everything and this thread was linked from another about what rubber tips can be used for the Vivi. I changed the tip to a tiny rubber one for a small CE2 clearo and it hit's great, I just need to find slightly larger rubber cartomizer-style tips to replace all the big hard plastic ones that are interchangeable. (I bet Kanger purposly didn't make the MT3 tip interchangable so they can sell us something 'new', then after that, they'll make an MT3 with changable head AND glass tank, so people buy more form them instead of one great product that lasts a long time).