I can deal without the health bar in AC, simply because when I run out the game has some sound cues and a very clear warning that you are going to die. The map is pretty necessary though, since the waypoint isn't displayed on your screen, but the weapon selection UI is anything but necessary. Besides, you don't even need that stealth indicator, if you're being spotted the game has this nice sound cue (read: alarm) as a warning.
Although for AP, it wouldn't work very well.