I'm not sure how you're associating complexity with beat 'em ups. As for kill cams? I would personally preferred it if the animating work done for kill cams was better spent elsewhere for something more consistently prevelant in actual combat.
I agree.
Could say the same for "voice acting".
But there must be a market segment that views this stuff as being crucial in a modern video game and who would see a game that didn't include it as being behind the times.
Of course, if and when the technology is there to allow verbal interaction between the player and NPCs, e.g., through a "kinect" or some such device, my view on "voice acting" ... which I thought would be so nifty back in the NES period ... might change.
I think the first PC game I played where something in the game spoke was Ultima IV and it blew me away.
Now I just see it as more in the way of a "be careful what you wish for" gimmick that people have come to expect but, wouldn't really miss if it wasn't there.
At least with the old text based conversation games, you could imagine whatever voice you wanted for the character, rather than actually hearing one you might not like very much.