Ha, I never really thought about the Western-centric (otherwise known as the America! Fuck yeah!) view of the universe that is at play here. I wonder if there are any parallels with the War on Terror? A shadowy organisation operating outside the rule of law - it's pretty obvious that the Illusive Man is Dick Cheney.
I guess that is all par for the course though, given that the US is the biggest market. I don't think you're going to risk anything like a Russian or Asian protagonist with a game with this budget.
As a corollary to that, most people including me, played as a soldier, so your audience is a pretty conservative one - best not to do anything to piss them off.
I also played through the last game on the Casual setting; I just had no appetite for the boring combat of the previous two games. I'm aware that the combat was better, and I guess I could have made it more interesting for myself by playing a biotic or vanguard, but I really just wanted to play through the story and get the trilogy closed out.
I didn't have Mordin or Garrus with me in the last game, so a lot of the Tuchanka sections felt slightly flat. I didn't realise that it would have been Mordin rather than the generic Salarian that would have played out that section until after I finished the game. It was well done, but there was definitely something a bit odd about it without Mordin - it was mostly Krogan posturing which I noticed in that section.
Definitely agree that the characters and some of the more adult themes - the genophage being the highlight - were the strong part of the trilogy. In the end it was a fantastic achievement, a good and sometimes compelling game, and it's weaknesses weren't too overpowering. The first game was probably the highlight for me.