I don´t know who it works, he said that it allows the artist/shader guy to put dirt, and distortions on the lens to make it looks like a real world lens with dust, moisture things that cause more aberrations on the real images and that make the light spots to bloom as a nice Glaring/glowing atmosphere, and that this was perfect for this (animation) work.
I know that´s the kind of thing we always do on post (me included), but i have to confess that i miss the lume lens, and the lens shaders on MentalRay, the lume applied directly on the 3d software looks much more richer and accurate than the one i put on Post production... SO, sometimes i use lume/glow as subtle post effects directly on Mentalray... As i said, not a MUST, but nice feature to have (on Maxwell).