Which is why people inject parts of real life into their games, even when the game has fantasy elements.
The missing word in your sentence is
some people.
The issue of "Injecting real life elements into a fantasy game" comes down, not just to taste, genre and expectations, but also an emotional component.
Let's take Watchmen. Watchmen is a movie that deconstructs the Superhero genre. That says, "Here are super-powered vigilantes that fight crime. What would that do to someone's psyche and personality? How would the world react? And how would these people behave, if the real world issues of morality are applied? Who is the good guy, who is the bad guy?"
For some people, that is awesome.
For others, that's horrible. Not because it harms the genre, but because for two hours, they want to
escape the moral ambiguidy of the Real World, they don't want to be depressed because this so-called Hero does something despicable because he's human, they want to believe in Good vs. Evil that good can triumph over evil, that the nice guy gets the girl, justice, hope and love are eternal, bad things rarely happen to good people for no reason, that the hero isn't in a Greek Tragedy where his flaws are his undoing, but overcomes due to the qualities of his character, the world
can be made a better place, and happy endings usually happen.
The same is with RPGs. Last month, there was a thread about Good Vs. Evil in this forum; some people vehemently defended the right for there to be Alignment absolutes in RPGS (Orcs are evil, killing the babies is not a morally questionable act, etc), while others vehemently defended moral relativism (The issue of Orc babies being a blank slate, with overtly evil tendencies, and killing orc babies causes a paladin to fall).
There was a very bold line drawn in the sand; the Absolutists did not want moral issues in their game; they wanted to
believe their character was Good, the other guy was Evil, and no question brought to their justifications.
Not because of a simplistic world view. But, at least for some (and I would wager, many), they
don't want to deal with that crap because they have to deal with it every day of their lives. For 4 hours every weekend, they
want to be a knight in shining armor saving the princess because that's
not real.
Fantasy, in the truest sense: an escape from "Stuff Sucks".
Bringing this back more in line to the current topic, then, one can also take this view about an RPG or a movie or whatnot. Realism can be separated (and, desired to be separated) from cinematics or the game world, because that person is
wanting something unrealistic to begin with.
For these folks, elves dieing of syphilis is totally counter-productive to what they seek in an RPG experience.