Gratuitous

The aggression was provoked by all those gratuitous insults.

As Paul says, it is really perfectly gratuitous ("es ist im grunde reine willkur") to call the case we have in German (and Old English) a dative, for besides the functions of the dative it fulfils the functions of the old locative, ablative, and instrumental.

Also mentioned is the Rev. T. Stock, who has a tablet in St John's church [Gloucester] and "who with Raikes established the four original Sunday schools in this parish ... in 1780. From this small beginning sprung that gratuitous system of Christian instruction which has covered the face of England and Wales with schools."

gratuitous violence

Good to see you Mr. Bond. Things've been awfully dull 'round here. […] Now you're on this. I hope we're going to have some gratuitous sex and violence!