You know, it's funny that you mention Willem Defoe not looking Mexican when the first thing I remember about the movie is that Mexican extra who looks JUST LIKE HIM.  It's funny.

You're totally right about the thing being too wrapped up and detailed, I agree with that (I actually don't remember much about the movie's plot, most of my memory is Johnny Depp with the missing eyes).  I think this was meant to be the "big" film in the style of "The Good, The Bad, And The Ugly" but even that was pretty simple and straightforward.  The thing about movies where the protagonist is wrapped up in something like this is he has no big personal stake in it, not like when he's fighting for love or the one big payoff or anything like that.  It's like he's a cog in a machine.  And people don't want to be cogs in a machine, why would they want to watch movie heroes be that?