We've got a couple of digi-movie cameras, but just don't use them, and it's the inability to interact when using them that is the main cause. At least with still photography I can take a photo, then carry on, even if sometimes the interaction is about getting them to let me take an alternative pose!
I think you also raise another important issue - that of family photography generally. I think it's something not taken seriously by what we might call 'the photography establishment'. Family photography appears to be regarded as the preserve of snapshooters, not a serious endeavour for serious photographers. A quick look through a photography magazine or book is unlikely to reveal articles or chapters on photographing your family. Is it just portraiture, or does a different dynamic put it into a different or sub-category?
Bill, Yes, but... I think family photographs eventually can gain value as historical artifacts. Take a look at the early photographs of Jacques Henri Lartigue to see what I mean. Lartigue certainly was a serious photographer, from a very young age, and those early pictures have value that goes far beyond the fact that they were "family" pictures.