(Kant's view is that metaphysics is concerned with the fundamental structure of rational thought about reality, rather than reality itself. This is why it is non-empirical and can be a source of knowledge.)
Most of us do metaphysics at least some of the time, whether we realize it or not (I need some examples here). Even anyone who argues that metaphysics is ill-conceived, or hopeless, or that there is no such thing, is doing metaphysics. So we might as well learn to do it well.
Even if doing metaphysics will not give is the answers to our metaphysical questions, at least it might help us to see what the possible answers are, and what can be said for and against them. Thus it might help us to develop a more informed opinion (rather than just hold beliefs dogmatically).