As far as shades of gray not working in a "summer blockbuster" I would say that TDK has many shades of gray, with an interesting well organized story. Shades of gray don't mean no compelling story, or lack of conflict. This could be a smart, yet entertaining summer film.
I'm sure that some will see this as "too complex" to fly and too much detail the new fan won't want. I still think it could work.
Right.
The Dark Knight establishes a minimum baseline of moral complexity that you can put into a blockbuster and still make a mint. But complexity need not mean only darkness and shades and grey. Optimistic, humanist values can be complex, too, if properly tested against their opposites in a dramatic story.
Pike says that the Federation is a "humanitarian and peace keeping armada". Let's put that to the test, maybe with a Klingon plot as suggested by the quoted poster, maybe with something else. (And if you want your moral complexity in the villain himself, well, let's just say of the four main Trek villain races: Klingon, Romulan, Cardassian, and Borg, it isn't even remotely close which of those is the most morally complicated....)