In all seriousness... glass is heavy to ship, and a pain in the ___ to clean up if it breaks. With that said, it's absolutely the best way to contain really powerful stuff, like 100mg strength nicotine.... but for the average little bottle of e-Juice, it's probably not all that necessary to pay the extra shipping and all the extra other hoopla that goes with glass.
What I would love to see, is if they could make some of the new plastics more flexible, and to see what their leaching rates are, if any. (i.e. what if Nalgene could come up with an LDPE equivalent.... THAT would be some fatastic nerdy factoid reading)