Got a New Maglite. What is the clear plastic blob on emitter?

So my 4 d cell mag lite that I have had for 20 years got stolen, Yes I am very sad. But because of that I was willing to buy a new one. I bought a 3 cell and I believe it specs out to be brighter than the old bulb style. I took it apart and was looking at the emitter, I believe that is what the led/ light thing is called.
So what is the purpose of the clear rubbery drop of whatever on the emitter. I have seen it also on bigger builds etc. I figure its for heat or reflecting light.
What is its purpose?

protect the LED and make a more "desirable" beam pattern.

EDIT: If you look closely at the LED you will see small bond wires. Those are VERY fragile and once broken you have a dead LED. Although LED swaps are easy, the average person doesn't know how or want to do that. By putting the dome on the LED, it will last longer and less risk for the manufacture.

De-doming the LED allows for a warmer tint and more throw

Spot on.

The dome also increases light output by altering the index of refraction.

Some very technical info here: Flashlight Optics - Dome, Dedoming and Throw | BudgetLightForum.com

Of interesting note, not all maglites have domed LEDs. The new LED Solitaire has a luxeon Z, if I remember correctly
http://www.philipslumileds.com/uploads/415/DS105-pdf

But yeah, it is an efficiency optic that helps extract all light from the LED. Without it, some light would be lost or made unusable.