[Utsuro no Hako]

Originally Posted by Aphrah

Perhaps. But it also might've cost more to do so? That, in turn, may have lead to worse pacing or animation. It doesn't really matter in the long run, as it's a fairly minor detail. *shrug*

Well it is unusual for a studio to not seize every opportunity to add an insert song or alternate ED to the OST. I suppose they didn't want to spring for the rights to the song, but, though it pains me to say it, they could've gone with a public domain Christmas song.