DH says fighting with packaging, wrestling with hard-to-assemble toys, searching for the right sized screwdriver and so on are an important part of a traditional family Christmas morning, and will teach DC patience and perseverance. He also says the gifts won't 'feel new' if they're out of their packaging.
I think it makes more sense to unpack/ assemble/ put batteries in/ charge up now, pre-wrapping, so that when they open a present on Christmas morning they can just crack on and play with it. I would also note that after the opening DH will be buggering off to work, so he won't actually have to do any of the aforementioned faffing. I'll be left dealing with the inevitable tears when I build one child's thing before the other, or can't actually clip the crucial part on...
Am I being unreasonable?