A game with good difficulty was Far Cry 2. Its easiest difficulty was as easy as very hard New Vegas but it's very hard was pretty [censored] hard. Example: the char dies from one heavy machinegun shot. It wasn't constant save'n'reload but the char simply couldn't assault enemies guns blazing. When there was a big gunfight between two enemy groups it totally did not feel like "hey ill just stick around and kill everyone" but "oh[censored] I gotta get out NOW". The difficulty was optional, so no one had reason to complain about game being too hard or easy.
What comes to new vegas difficulty I'd rather have it so that the courier takes part in decisive incidents and just has to survive through them, not kill everything alone and always make the initiative before something happens. So that he fights alongside with ncr or legion in big battles and his little actions eventually turn the tide. The player has too much control and this makes the rest of the world seem weak and pitiful.
In some cases the game reduce's players control in good way. For example when you try to reach the Boomers there's no option to kill the artillery gunner or try to resist the artillery fire, you just have to make a race to the fence. In that situation game forces the player to go along its rules, the player is not in charge and this makes the him feel humble and not so omnipotent. There's not many situations like that in the game. Another one would be if you come across with BoS for first time while at low level. It's a situation where the npcs totally show that they are not to be messed around.
All I'm asking from the npcs is some show of force.
At least half the games I've ever played involve playing as a character that is Death incarnate if he/she chooses to be. No offense, but how is this new?
Because the courier isn't a superhero but a man. In games where the player takes out armies alone his capabilities of the char's badassery are thrown at player's face right away so there's no question what the game is all about. In addition in such games the character is actually given tasks like "Go save the world" while courier has the same capabilities but he gets some errant quests and is threated as some ordinary dude by most npcs.