It's probably a dumb question... if you're thinking critically about it, you're probably not part of a family of 3 living in a 2800 square foot crackerbox and wishing you'd borrowed that extra $50k for the 3200 square footer so you'd feel superior to your neighbor. It's not really a new question, a few people have been asking it for years, but the mainstream is just now realizing that it might be good to ask more than "How much will you loan me?" when they're choosing a house, and it's driven more by the crumbling market than any realization that they haven't opened the door of that 'guest room' at the other end of the house in a month.
I've found lots of references to a report called "Housing Facts, Figures & Trends 2004" from the National Association of Homebuilders on many sites, but I could only find the actual report second-hand here. It's not on the list of publications the NAHB make available on their site that date all the way back to 1997. I can understand why the NAHB might prefer that people not think too much about this... if people realize they don't need a 3,000 square foot house, they might also realize that there are lots of 2,000 square foot houses already out there that they could buy.
Among the interesting tidbits in the report... in 1970, the average home size in the US was 1,500 square feet. By 2004, the average had ballooned 2,349 square feet. At the same time, average household size dropped from 3.14 in 1970 to 2.59 in 2000. (according to US census data.) What are we doing with all that extra space, besides paying to heat and cool it? Master bathrooms bigger than my bedroom, media rooms, formal living and dining rooms that get used once a year... it's crazy!
I think this all ties in with the sprawl of suburbia... if the houses that are already built closer in are those dinky 2000-square-footers they were building in 1990, well, we've gotta go out further... it's just a little more commute time, right? I wonder at the actual driving forces behind it... is it more the fashion and getting ahead of the Joneses? (But not Mother Jones, of course... they don't approve.) Perhaps instead it's the drive by homebuilders to continue to sell new houses, offering bigger, fancier, flashier McMansions in ever more gated and restricted communities so that people will think their existing home is too small in comparison to those of their acquaintances and coworkers.
I live currently in the 3rd house I've owned, and it's a Goldilocks situation... bigger than the first, smaller than the second; younger than the first, much older than the second. For the moment, it's "just right." The 2 of us plus 2 dogs live comfortably in a 1500 square foot house originally built in 1952 (it was built at about 1200 sq. ft, a previous owner added on a room and a 1/2 bath at the back.) I'm sure I wouldn't mind having a little bigger pantry or another cabinet or two, but we can both work in the kitchen and cook good food, and it helps us follow Alton Brown's "no single taskers" mantra. Even with 56-year-old windows, it doesn't cost me an insane amount to cool (and of course in Texas the cost to heat is generally negligible, I could spend the winter in a tent.)
My middle house was new... most of the houses close to my office were in new developments, so I gave it a try. At 1750 square feet, I built the smallest plan offered by the builder, and spent a little extra for some energy efficient upgrades. My house was nice enough, and different from the other houses because most of my neighbors built as much house as they could get financed; there was only one other house on my plan in the whole development. It was still a very "suburban wasteland" experience, with restrictive covenants controlling everything from the color you could paint your trim to how tall your grass could be, all dialed in by the developer and written into the deeds when the tract was subdivided. The results are very beige... if anything is too different, the "architectural" committee of the HOA (none of whom have any architectural experience, of course) will come to hassle you.
I have vowed never to be subject to an HOA again, and it's entirely possible that I'll never own a house over 2,000 square feet. I don't think a well-designed house NEEDS to be that big unless you have a big family. I hope to design our next house, though depending on where David does his residency it may be the house after next. Hopefully I'll remember my small-house prejudices when it comes time to do the design work.