Racism and SF: "Alien Nation"

>>Why do people feel the need to exaggerate a real problem -- like racism -- to this extent before they feel comfortable addressing it?<<

Telling a real story in allegory is a very old, popular, and effect method of putting delicate or dangerous topics at a safe remove so they can be considered and discussed. For example, if you set up aliens to be oppressed, people aren't likely to say, "Oh they're not really being oppressed," because the aliens aren't real (although oppression is). Tell a similar story with black (gay, female, Jewish, etc.) characters, and some people immediately claim that it's "implausible." Furthermore, it grants access to readers who might gladly read far-out SF but wouldn't read near-future mundane SF; and similar ideas still roll through their heads. So overall, the safe-remove technique expands the audience and the opportunities to explore an issue, while minimizing some of the dangers.

>>I'd like to hear of SF courageous enough to tackle real problems realistically; SF that presents _possible_ or likely futures, their challenges and potential solutions.<<

That's another branch, and it has its writers and fans too. "Near-future," "realistic," and "mundane" SF are some of the names used for this subgenre. Some hard SF stories fit here also. Baen has a couple of anthologies about space exploration along these lines. It's good to have multiple options.