I think the answer lies in the clever design, so you don't end up with any 'dead space'. That way you can your square metres into having larger single rooms, rather than having multiple rooms spread out all over the place. eg, one decent size kitchen/family room that you can move your furniture around in as you need to is worth more in my mind than a small kitchen and a small dining room that's only big enough to fit a table into, kwim?

Our house was built in 1974, and the entire entrance room/hallway is a complete waste of space, it's not the right shape or size to be used for anything other than walking from room to room. I compare that with the townhouse my sister bought recently, and that had a wider hallway, which had functional storage, bookshelves, a study/workspace, and a laundry (in a cupboard - but quite large) so that every bit of wall/floor was actually functional. Having said that, ours is the good old L-shaped lounge/dining area, with an open plan kitchen and we live and entertain quite adequately in that space, even if I do find myself wishign some times that they had built the room just 1 metre longer (to allow for more storage space...oh for a buffet LOL).