Well, for me personally, I generally like adapted scripts better because I understand the context better. I guess it's more grammar nuanced. I love watching in both audios myself.
When <harmony/> had its two day run in theaters here they were seperated by their audio, one day had the JP audio and the other day had the English audio. It's not like every anime movie shown in a theater in the US has to be dubbed. Hell, Kizumonogatari was shown in theaters and obviously Monogatari in general was never dubbed. I wouldn't really call it a need, per se, just you gotta have as big of a reach as possible.