Which is still a ridiculously judgmental thing to say. What does "necessary" even mean in this context? It's fiction. It's entertainment. It's about having fun. Nothing about it is "necessary" in the sense of sustaining life or earning an income or whatever, but it stimulates our minds and imaginations. And a lot of us find it fun and stimulating to undertake the creative experiment of trying to reconcile the fiction with reality. So that is no more or less "necessary" than any other way of engaging with a work of fiction.
What are you even talking about here? Earth is clearly depicted in Trek as a world of central importance to the Federation. Starfleet Command is based there, the Federation Council is based there. It's clearly the capital of the Federation. So it makes as much sense to use Sol as the reference point for delineating the Alpha and Beta Quadrants as it does to use the Greenwich Observatory in London as the reference point for delineating Earth's hemispheres. It's a decision that was made for historical and political reasons in real life, so it's entirely logical that an analogous cartographic choice would be made in an interstellar civilization whose capital is on Earth.
"Must" has nothing to do with it. If you don't want it to match up in your own personal version, then you don't have to make it match up. But a lot of us do find it fun to bring as much reality into it as we can manage.
It doesn't have to be all or nothing. They say the best lie is the one that has the most truth in it. And the same goes for fiction. No, it can never match perfectly with reality, but incorporating as much reality as you can gives it verisimilitude. That's how Roddenberry himself approached TOS, TMP, and TNG. He consulted with scientists and engineers and think tanks, brought in reality where he could, and ignored it where he needed to. He created a fiction, yes, a universe different from the real one, but one with elements drawn from reality to make it feel more believable. That's a perfectly valid and common creative practice. Storytellers do it all the time: they create unreal worlds yet ground them in details drawn from the real world to give them verisimilitude. Arthur C. Clarke set The Fountains of Paradise on a fictional island in the Indian Ocean, one farther south than his home of Sri Lanka so that it would rest on the equator, but otherwise he based it heavily on the real history, geography, and culture of Sri Lanka. Diane Duane wrote her Young Wizard and Feline Wizard novels in a fantasy universe where magic is real, but set them in a very accurate and well-researched version of New York City. This is verisimilitude -- literally, similarity to truth. Not actual truth, but a fiction that bears enough resemblance to truth to feel as though it could be real.
So you're absolutely wrong to say it's a waste to incorporate elements of reality into the fiction. Doing your homework and making the effort to build more verisimilitude into the fiction is never a waste. No, it isn't absolutely "necessary," but that's a nonsensical standard to apply to fiction. There are many ways of telling a story. Some stories are set in completely invented fantasy lands, while others are grounded in the real world while still containing major divergences from it. Neither approach is wrong.
