I don't think you missed anything specific (or I missed it, too). It's a big house for a small family. It takes a lot of work to keep a house that size clean, let alone decorated. (Remember, there are servants' quarters!) Mom has a full-time job. Dad probably could help more with the housework, but I'm guessing he spends most of the day at his typewriter. Or drinking. The bedrooms, kitchen, and TV room all seem more "lived in"; they probably don't spend much time in the other rooms of the house.

It's a little unusual, but not inexplicable.

I never thought about the number of unpacked boxes, but FWIW the last time I moved house some of our things did, indeed, remain boxed up for literally years.