Many other countries similarly changed the name of their respective ministries, reflecting the ideal (if not the fact) that war should not be pursued for gain or used to resolve international controversies.
Actions trail behind ideals; ideals are set to remind us of how things should be even if we don't live up to them. Renaming the DoD to DoW reflects an aggressive, violent and ultimately predatory posturing that the West had chosen to abandon after WW2 and many millions of deaths.