A key advantage of some forms of speculative fiction over mainstream works is the abilty to address the core of an issue through a metaphor rather than a literal engagement of the issue, with the attendant baggage that would bring.

This is not always appropriate to the story being told, of course. As a study of the modern American city and its social problems brought about by how bureaucracies function and how institutions grind down the abilities of people who want to improve the system and promote conformist 'game-players' instead, THE WIRE would not even remotely function as an SF genre piece (although I now confidently await the first SF TV show to be called "THE WIRE in space," it'll happen one day). That show had to be set in a modern, real American city and be based on true stories for it to work and have relevance.

However, its study of how power sometimes corrupts the weak and the examination of the motives of those who want power or don't but have it thrust on them anyway and how they cope is something that is equally well-handled in A SONG OF ICE AND FIRE than in a 'realistic' story, because the theme is broader and more widely applicable.

Similarly, whilst the dwarf-racist story was mentioned somewhere upthread, there is actually an example of how tacking racism through metaphor has worked in the past. In 1968 an episode of STAR TREK featured an alien seeking refuge on the Enterprise because he was being hunted by another member of his own species based on 'racial inferiority'. When the hunter showed up, Kirk and co. were totally bemused as the two aliens were identical, having half-black and half-white faces. It is only later that they realise the 'superior' race is black on the right side of the face and white on the left whilst the 'inferior' is reversed. By removing the issue of racial prejudice from the real world where there is a huge amount of baggage that comes with it, Roddenberry instead broke it down to its bare basics: disliking people because they look a bit different and have a different culture. According to Roddenberry, quite a few people complimented him and the show for raising the issue in a manner that would otherwise be impossible for a mainstream American TV show in the late 1960s.

In these and many other cases putting 'distance' between the theme or idea and the reality also strips away the distracting baggage of the issue and allows it to be examined from a different vantage point. In some cases it is inappropriate and doesn't work, but a lot of the time it does.