As I understand, MWI is empirically equivalent to other interpretations of quantum mechanics.

It's also empirically equivalent to the theory that "The lady down the street is a witch; she did it."

a metaphysical commitment

Democracy! Freedom! My enemy kicks puppies! (Physics is just called physics, even when it is unintuitive.)

You should be able to justify any particular course of action without a metaphysical commitment to the reality of unobservable components of the universe's wave function.

No I shouldn't. I should use the best possible model that can be constructed of the universe's wave function based on the evidence available and ignore any demands that I justify my decisions according to systems that are artificially crippled.

It so happens that all my decisions can be justified using a single world map but this is entirely an artifact of my preferences and nothing to do with epistemic or decision theoretical considerations. (It would be weird and possibly 'insane' but not irrational to have decisions that were not reducible in this manner.)