People who may be looking for his work may see the cover and judge at once that it isn't what they're looking for, and people who are huge fans of the game will think it is some crazy action book, flip through it at Barnes and Noble, and get annoyed by the fact that it's more intellectual that action-packed.
So? What about the ones that don't get annoyed that its not like the game and decide to give it a go anyway? The fact is that they would have picked it up and flicked through it and in a lot of cases they probably wouldn't have even got that far.
I also don't really see it being a problem for people who are actively seeking the book out. There are still other editions of the book in publication. Besides, in my case anyway I'd probably be more interested in having a closer look at the book with the ridiculously out of place cover while browsing the usually muted tones of the classics section at the book store. (That is if it doesn't just get bundled away into the 'tie in' section and be doubly ignored anyway)