Leases allow dealers and automakers to arbitrage the price difference between what you get for a used car and what they get for a used car. If the dealer thinks the resale value will be great at the time of the lease, they'll lease you the car and then sell it for more than they would have gotten for the MSRP minus the lease payments.

There are ways where a lease makes more sense than a purchase, but it's still a tricky proposition. Nissan was offering me a Versa lease, unsolicited, for $79 a month, $1000 down, two years. That's basically $3k out of my pocket to have a car for two years. 2016 Versa is MSRP $12k right now, figure prolly $11k out the door (cheap cars have less wriggle room). 2014 Versa at the used car lots right now is about $8k; trade-in is prolly $5500. Makes sense to me to lease the versa rather than buy it. Nissan, on the other hand, can call that a "factory certified pre-owned" Versa and sell it for $9k to the right schmuck. The dealer has a chance to make $12k on the car anyway, and the accounting rules for recurring revenue (like lease payments) mean they get to show it as forward revenue, rather than past revenue. Not only that, but they get that much more of an opportunity to up-sell their customers; we bought a 2009 Fit and I would say we average 2 flyers a month from Honda dealers offering to buy it back in exchange for a new one because (A) Fits sell really well at dealerships (B) if they can convince us to take their shitty trade-in they get to sell us yet another car.