Wrestling with Metaphysics

As I read more about Idealism and Realism within philosophy, I find myself increasingly concerned with my reactions to metaphysical arguments. I can't help but find many to be futile speculation that can never hope to be proven. Some even try to reason out the behavior, structure, or existence of things the thinker even acknowledges can't be accessed by human beings. I have immense trouble understanding these arguments because the logic they use is so profoundly different from my own. Causality and evidence seem to mean nothing in much of metaphysics. It's eerily similar to religious arguments and reads like pseudoscience. The book I've recently been working through even shows disdain for the scientific thinking because of its insistence that evidence and empirical data can explain the universe to humanity.

I want to be open-minded, though. I want to avoided denouncing metaphysics entirely and find value in it. A recent article in Nautilus interviewing Bas Van Fraassen pointed out that ideas like String Theory can be seen as metaphysical which surprised me since I had never considered scientific theories to be so. I assumed the philosophical discipline gave way to science as evidence and data were uncovered, thus obviating the need for metaphysical argument. Now I wonder if it's more complicated and nuanced. Fraassen seems to call scientists to embrace a less definable reality where function and pragmatism are more important than a completely defined understanding of the universe. Some things are simply unknowable and may be forever areas of frustrating speculation. The point he seems to make is that these areas provide no direct benefit to humanity and thus should be avoided by science. Philosophy can wrestle with them since it is designed to do so, but I even questions that. Shouldn't philosophy aim to be useful to humanity in a real way, as well?