Personally I don't get the obsession with 4 doors on a car. On any sedan smaller than a Grand Marquis (which is literally pretty much every sedan nowadays), the back seat is so cramped that it's useless for anything beyond kids who don't realize they're crammed in. In that case, why the need for 4 doors? Kids aren't going to complain about climbing into thru a two door. The back seat is cramped with or without the extra doors....
I get it for SUVs and full size trucks where the back seat is actually roomy enough to deserve it own doors. I just don't see the point for the focus/fusion sized cars.
I can agree with you regarding people's obsession with 4-door cars but understand that much of it depends on the driver's life style and needs. I'm single, don't have any kids and have little use for access to a rear seat. Even before I had company cars (Demo's) my vehicles were personal... 1967 Ford Fairlane Convertible, 1971 Ford Torino 2-Door, 1974 Mercury Cougar XR-7, 1976 Mercury Cougar XR-7, 1980 Pontiac Firebird (Oh no! Big mistake!), 1974 Ford Thunderbird, 1983 Dodge Charger 2+2 (Fun basic, stick).
When I left the entertainment business and went to work for the dealership I started out driving a 1986 Escort, then a 1986 Escort GT, 1986 Mustang, etc. until I became Merchandising Manager 6 months later and started driving a 1986 Thunderbird. FYI... Our dealership was know throughout the Northeast as "Birdland" and was one of the top selling Thunderbird dealerships thanks in part to Don Imus doing live commercials for the dealership every day for 48 weeks per year. When the traditional Thunderbird was discontinued after the 1997MY, I drove several Taurus sedans and then switched to Probe GT's until finally switching to Mustangs with a 2004 Mustang GT. I have the benefit of driving any vehicle I want thanks to my seniority (32 years now!) and managing the new vehicle order bank. And even though many or most of our Mustang customers park/garage their cars during the winter, I drive the Mustang ever day unless we're going to get a foot of snow. I'm only .9 miles from the office but open the dealership early each morning and have a difficult hill to navigate.
Customers today love the practical aspects of SUV's with the higher, driver command seating and the 4WD/AWD capability along with the utility benefits that have basically become the replacement for what was once what we called a station wagon. And along the way, the SUV's (CUV's included) have attracted customers that once bought minivans. The Market has changed but even so, there will continue to be a Market for 2-door vehicles like the Mustang. Yes, the Mustang is both a niche vehicle as well as a halo vehicle. Fortunately, Ford has been very smart in taking the Mustang global and continues to develop/enhance the Mustang to meet both domestic and foreign market demands, etc.