My honest reason (and this is coming from a guy with no stake in the game or significant physics or biology knowledge) is that it would just be cool as fuck, and that exploration is valuable in itself.

I'll acknowledge that that is wishy-washy language, but that's kind of my point. I'm not sure I can point to an objective "good" that comes out of it, but I also don't know that that's the norm for these kinds of things either. It might have been hard to say that going to the moon was an objective "good" outside of one-upping the Russians, but I do think it's good that we did it, even if I don't really know how to quantify why.