They were kind of leaning this way, then kind of not, and now I guess they're going all in. The Ford Sedans, like the Ford Mustang, are about brand loyalty and getting people onto the lot. In raw numbers though, Ford sells trucks.
According to Wikipedia, last year they sold in the North America alone over 1 Million Ford F-Series trucks, 300k Ford Escapes, and 270k Ford Explorers.
In comparison, last year they sold about 48k Fiestas, 170k Focuses, 209k Fusions, 40k Tauruses, and 81k Mustangs.
There's your difference in raw numbers.
I can't think today, so here are some random thoughts.
1) I see more Ford SUV police vehicles on the road than I see Sedans. I know police officers, everyone I talk to hates the sedans Ford, Chevrolet, and Dodge makes because they're too cramped but everyone loves the SUVs. The guys repairing them miss the hell out of Crown Vics though.
2) During the '80s, '90s, and early '00s, Ford's cars had a dodgey reputation where their trucks were often still highly regarded. Which would you be willing to buy? A Ford Fusion or a Honda Accord? Why?
3) Fleet sales are probably a factor here, but that's more than I know how to look up.
4) There's a larger profit margin in Truck sales than Sedan sales. Don't ask me to explain why, cause I don't know, but that fact is part of the reason why GM gave Pontiac and Saturn the axe when they were restructuring but decided to keep GMC even though everyone and their mother pointed out that Chevrolet, Pontiac, and Saturn all sold different cars while GMC trucks were basically upbranded Chevrolet trucks.
5) The Mustang, like the Corvette, like the Toyota 86, like the Mazda Miata, is a flagship car. It's not about sales numbers or profit margins for those cars. It's about keeping the brand in your mind by creating excitement when you see them on the road and letting you know the company exists through T-Shirts, Calendars, Magazine Ads, etc. The Mustang is core to Ford's image. The day they announce they're gonna stop making Mustangs is the day they decide to announce they're taking the company in a completely different direction.
6) The Mustang is cool. The Ford Focus RS is fucking sick.