Fair criticism. What is so intriguing about E8 is that it pops out of physicists equations in a lot of different areas. There's likely something fundamental about it. But you're right that the definition of how it is going to change things is a little vague. It seems to me one of the biggest barriers is the complexity of the description required. Sampling a single configuratin of the E8 out of 60 gig of numbers and formulae is going to be very comptationally intensive. Will probably limit it's usefulness until computers get faster.
But kudos to the folks who did this. It's a massive accomplishment that may be very important.
From this great article http://aimath.org/E8/ from the group's website:
"The magnitude of the E8 calculation invites comparison with the Human Genome Project. The human genome, which contains all the genetic information of a cell, is less than a gigabyte in size. The result of the E8 calculation, which contains all the information about E8 and its representations, is 60 gigabytes in size."
Quite a feat.