I had a course last semester over whether the foundational axioms of set theory (the basis of mathematics) entail the actual existence of the entities they refer to (sets) or whether those axioms are fictions.
Also, you're assuming both that we can learn enough about the universe to make any area outside of mathematical physics obsolete, and also that there's only one type of question we as human beings are legitimately concerned with. The first is questionable, the second is atrocious.
You can build an entire course on that? Well of course some mathematical concepts are fictitious. Is it even possible to represent a repeating number in the real world? It's all theory. The important part is when its used to describe how things work.
And what's the point of learning as a race if you don't hope that we will eventually learn how the entire universe functions? There will come a day when people are judged for their usefulness to mankind, and every single person can be quantified on how much they move the race forward or hold everyone back. It's dystopic, but it's progress in its purest form.
And math is the single most important thing anyone can learn. It's what moves everything forward, and what isn't known through math is filled in by philosophy, art, religion, and bad excuses. If humanity doesn't die on Earth before we can escape this wretched little planet before all our resources are gone, and we freely colonize the stars, our understanding of everything will increase until we have the power to create our own universes and transform ourselves into beings that transcend these inefficient fleshy sacks of bodies and digitalize our imperfect brains. Call it grim and atrocious all you want. Call me a fool and an idiot for believing it. Call me a monster for wanting it, but the more we learn about how the universe works the less we'll need those old diversions of philosophy.
There is no "should." If you don't care about TES, then quit. But you've said that you do, so obviously there's something you like here, something that keeps you going. If its just the metaphysics that you don't care about, then ignore them. None of this is either/or. It seems to me that you more or less understand all this stuff, your problem is with accepting it. There's nothing we can do for you on that.
I really do love TES and Tamriel and everything, but it makes me feel strange investing myself in a world that is defined as a dream.