Neither do they.
This does not constitute a sweeping change for Goose Island since the beer apparently had a pretty minimal production. However, they justify dropping a "small volume brand" for the purpose of freeing up space so they can brew interesting beers. That does make a tiny bit of sense. On the other hand... What??? Didn't they just sell to AB for exactly the purpose of expanding without cutting brands?
Perhaps it's nothing, but the wildly speculative side of me* thinks that this was probably a result of corporate cost analysis and perhaps a desire to test the waters of public perception at brand-cutting. We'll continue watching. For the time being, I'm still enjoying Goose Island IPA.
*that is also the side that writes blogs, if you were wondering