Okay, finally behind a keyboard so I can reply in (slightly) more detail, though frankly you can write whole books on this subject.
Speculative fiction in general, and sci-fi in particular, is at its core about discovery and change. When you peel back the layers of tropes and gee-whiz flashy bits (like blue-skinned alien women or giant robots), the core is about exploring and discussing ideas that, for various reasons, can't be properly discussed and explored in any other format.
What does it mean to be human in a world with sapient machines? What is the dividing line between human and non-human in a world where cybernetics can replace 80, 90, 99, 100% of the biology with metal or data? Do connections with other humans even matter in a world where there are a thousand AIs or aliens for every human? How would humanity adapt to a world where the laws of physics are so very different than our own; would they even be able to be considered human in the first place? These are fascinating questions to ponder, and potentially critical given the speed at which technology has been advancing lately, and speculative fiction is a great vehicle for that.
The hard/soft SF divide, if there even is a true divide and it's not more like the Kinsey scale, is a natural outgrowth of the sheer diversity of questions that can be asked under this umbrella. What's interesting is that, as
@Coda said above, what is considered "hard" and what "soft" is itself changing as time goes on: as general scientific knowledge increases, the expectations of how much scientific rigor is required to be considered "hard" also increases. Asimov tried to be a hard sci-fi writer in the first half of the century, but it really wouldn't have occurred to him to get the kind of physics help that, for example, Carl Sagan did to put together his system of traversable wormholes for
Contact.
Hm, I had more to say about this, but really this is already getting far off-topic. I think for the purposes of this thread the statement I made in the previous post is the most important: these kinds of debates are in many ways the core of what sci-fi and speculative fiction are about, as they let us explore ideas that are either too abstract, too politically charged, or otherwise unavailable to be discussed outside of fiction, but it's important to keep an open mind and respect people even when they disagree, perhaps
especially if they disagree.
Huh, and here I thought the Shiplords' rage was because they thought they recognized their great enemy, the one they
actually built all those War Fleets and the like to fight, then felt pity for Humanity when they realized that we were still a bunch of ignorant monkeys who accidentally learned how to make a steam engine out of twigs.
