Well, the author of that Wikipedia page certainly things that Gorsky should get more credit!
He does get far less recognition in the west, I think in part because he was the one that stayed home. Fokine came to the west along with the Ballet Russe, and although he himself went back and forth, his works became identified as the 'revolutionary' ones -- the reaction to Petipa's formalism. Gorsky's changes to the corps are most obvious in Don Q -- they really are a more dynamic, expressive and naturalistic element in the work, but you're right that we tend to give Petipa the credit for the whole, including those changes.
In general, we think of authorship, even in dance, as a singular phenomenon -- one person gets the credit when things go well, and the blame when they go badly. There are plenty of examples of works that were created in a partnership at the beginning (not to mention the more piecemeal additions/emendations/recisions that fill dance stages everywhere) but we like to think of the "text" as the product of a solo effort.
Gorsky, as I understand his work, didn't turn his back on traditional virtuosity in quite the same way that Fokine did -- if you look at Don Q, most of the bravura elements are still there, but they are interspersed within some major level hubbub in the corps. I don't have any evidence to back this thought up, but to me, this kind of stage action seems very like the early films of Cecil deMille, with their active crowd scenes intercut with more specific dramatic action.