Why Science Fiction?

The best answer to this is why not? In the Science Fiction Milieu, you can discuss any subject and include any situation or genre, whether it be romance, action, adventure, or yes, even an adult subject matter romp! I have learned that in my experience, SF is the genre to stave off shock due to social and technological changes sweeping through our society today. SF also tends to reflect the political climate, either as a coping mechanism or as a mechanism of reinforcement as well. It's an escape from reality as well as an instrument to perform a thought experiment in the best tradition of Aristotle in the ramifacations of change in our social dynamic as a whole from the macroscopic scale to the microscopic with subjects like theoretical societies (Incidentally, this leads to an author licensed FREE download of the book, Freehold in several formats sponsored by Baen Books) or the other end with stories on the ramifacations of nanotechnology. The Old Masters of SAF, such as Robert A Heinlein also wrote on ethics and social values in stories targeted to both juvenile and adult audiences.

Fantasy can also be included with works like The Lord of the Rings, by JRR Tolkein, or the Chronicles of Narnia, by CS Lewis, who was a friend and contemporary of Tolkein.

So it boils down to several ideas here:
If you like romance, it's in SF
If you like action/adventure, SF has it
If you like politics, SF has it
If you like intellectual stimulation, SF has it
If you just want a trashy read, pulp SF has it