"Our greatest glory consist not in never falling, but in rising every time we fall."
The ways in which a person can die in a game are as varied as the games themselves. Furthermore, the effects of death on your gameplay are just as varied. You have Diablo 3 hardcore, in which death of a character is permanent and sets you back to zero, or games like Battlefield or Team Fortress 2 in which death is a temporary "you're out!" How that death comes about can matter a great deal; games are about learning and death should teach a player some kind of "lesson".
Some games accomplish this better than others. Take Day Z for example; a game I think is fairly well done but death in that game can often lead the player to wondering "Umm...what happened?" just as much as it can teach a lesson about survival in a zombie infested wasteland. Take the following video (not mine, belongs to a streamer) for example (don't worry, it's very short):
What lesson did he learn here? At best "Don't go near Elektro" or perhaps instead he learned "Don't crawl near Elektro". Situations like these can be counter-productive; they leave a player wondering what happened with little information about how they might avoid such a death in the future. Day Z is an example of a game in which death comes suddenly because a single hit can bring someone down.
There is a fix to this: SHOW the player what killed them, give them some sort of recap or replay. Now snipers in games like Day Z will hate this idea because a kill cam typically reveals their position and that killed player can come hunting them down. I actually once heard it decried as "unrealistic"...which it is, but so is a sniper sitting in the same spot for shot after shot. Assassin's Creed's multiplayer mode attempts to help teach the player but trying to "guess" how the opposing player discovered you...though it often becomes "Captain Obvious" and tends to miss the actual cause. This would be similar to "real life" sports, in which athletes will often watch replays of themselves or their opponents repeatedly to analyze what to do differently if they face the situation again.
Much of this however requires that the death was "fair"; that is that the player had some form of control of their situation. In TF2 a soldier who appears around a corner and unloads a critical rocket into your face...well hard to learn something from that (besides, never go around corners?). In games like WoW PvE your "death" might not have been your fault at all. Maybe another player missed a mechanic, resulting in a party wipe. I am of the opinion that games should try to limit these types of deaths. At the very least, they should make it clear WHY; at least to tell the player whether or not they were responsible.
Then you take a game like Planetside, WoW PvP or some of the Battlefield games; while player death can often feel sudden, it often takes numerous hits to bring the player down. Many complain that this is an "unrealistic" portrayal (not going into the argument about realism in games), however that longer time, while frustrating for the victors in that situation, often allows the player on the receiving end to understand what is happening and learn from the experience. They can ask internal questions like "Should I interrupt that spell or hold on to it?" "Should I alter my loadout to deal with that situation?"...the line of thinking goes quickly but can be surprisingly deep...involving the weighing of risks, analysis of the situation, comparison of values. The shorter form of death can lead some players to feeling as though they are slamming their head against the wall. Certainly they can learn from resources online, but I have found that there are some things even Youtube videos and forum walk-throughs can't teach.
Furthermore, I find that in simulating the "feel" of certain situations often means breaking some real life rules. Take Planetside for example; it may be a sci-fi game with poor graphics by modern standards, but it is the closest I have ever come to feeling as though I am on a fictional battlefield. Real War is not fun...people die randomly, painfully and suddenly...hardly something I want to experience in a game (a "real" war game would probably play more like a survival horror than anything else...maybe Day Z is on to something), I think most people want to play the movie version more than the realistic one. Not to mention, even if a player can take a handful of hits before going down, having a dozen people shooting at them tends to shorten that survival timer. However being able to take more than one hit also helps deter camping; giving players a reason to charge from cover on occasion.
Therefor I come to my conclusion, that straying from reality is often a better way for game designers to go, because it opens the game to a larger audience, makes it more approachable and makes it abundantly clear to players what did them in and how they can improve.