"What If" can be a wonderful question, and the setting for great stories. People will still read She years after the crop of novelists featured in today’s Entertainment section are forgotten dust. (They hit all the fashionable notes, and I’d rather watch paint dry. I think next decade's readers will agree.)
"What If," to yield a good story, has to have the rest of the environment stay familiar. If you have interstellar travel, and are writing about human beings, you will sooner or later have interstellar piracy and war. Familiar things. Too much "What If" and it gets hard to use the reader’s expectations. Think of what happened with the Marx brothers movies when they got full control--it was more chaotic and less funny.
A good "What If" can make you think, not just enjoy a good yarn. But if you immerse yourself in this, if "What If" is the sea your thoughts swim in, I’d suspect that your knowledge can wind up diluted in the flood of possibilities. We don’t always have a solid handle on things that aren’t part of our everyday work anyway.
The notion that we can define ourselves is clearly science fiction. When technology adds illusion to "What If" some people start to believe they can actually change sex. Or be unfrozen, resurrected, and cured. (As both Simak and Niven pointed out, why would future folks bother?)
The upside of "What If" is an optimism about problem solving—or at least that used to be the case with earlier sci-fi. I'm not able to say much about recent works. I gather quite a bit of the recent stuff is didactically PC, but that doesn’t get past my filters. Limited money and time... The downside of the upside is a belief that a few select wise people can solve problems for everybody, and ought to.
Perhaps these influences aren't overwhelming, but I seem to find small traces all over the place. Or I may be missing something, since I'm not plugged into pop culture very strongly.