Au contraire my fine feathered friend:
Living "in the moment' with 4 children living at home in a house built in the twenties, I can assure you the 2000sf is not enough space. it was fine when the kids were in elementary school.
We have just added about 800sf in a master bedroom and family room to our 1980sf 4 bedroom colonial. to be frank, there is still not enough room. when the kids grow up they are bigger, have more stuff, and need more room just to live and entertain.
The real issue here is as households mature, do they need as much living space as they had when their children were around? My wife and I are struggling with the desire to have enough room for when the kids visit and the costs of ownership for a house that may exceed our needs in the future.