That Business Week article is fascinating. Boys focus on the exterior while girls the interior. I didn't look too closely at the Lego Friends sets last time I was in Toys R Us but I'm interested to examine them now.
Certainly thinking back now to my sets the means to build anything but the most crude representation of the interior of a building was impossible. Some buildings (especially those you might designs yourself) did not allow easy access to the inside (I think we can all remember shaking a vehicle or structure we'd had a Minifig go "inside") but even some sets like the police stations that folded out on hinges only had a crude interior with maybe a desk and chair.
I digress here into Majorette and their Majokit sets (I owned virtually all the sets shown
here and many more) which were a French toy basically halfway between Playmobil and Lego. Building Majokit stuff was fun, a the buildings needed assembly, as did the sidewalks that formed bases for your little city. However, the interiors of all the buildings were empty. The police station, restaurant, all of them: wonderfully detailed outside, but nothing inside. No sergeant's desk or cell in the police station, no furnished rooms or even interior tables in hotel/restaurant. The chef had a hat and kerchief and utensils but no kitchen to cook in, all guests had to sit on the patio to be brought meals by the waiter who must have magic'd them into the platter he carried. Even at the time I thought this odd but I can now see it's because all the emphasis is on the exterior and what happens outside.
Consider: when you (assuming male) play the Sims, how long do you spend on the exterior of the house? You likely just slap on a texture, ensure there's enough windows to keep the light levels high and then go in to ensure there's a toilet, shower, fridge, sink, bed, oven and TV. Your partner (assuming female) will likely spend far longer agonizing over the decor, as well as the landscaping outside and accessories like matching lamps inside.
Or more simply: do you look inside the houses in Viva Piñata? I bet your missus does.