The original reason for leases was that the auto industry needed people to buy new vehicles more often in order to keep their production lines going. They came up with leases as a way to keep the monthly payments affordable but improve their profit lines and get people hooked on the idea of changing vehicles fairly often. The write-offs as business expenses were part of the rationalization they made up for people to go ahead with leasing.

Changing vehicles every 3-4 years is fiscally stupid except in very rare circumstances and it makes no fiscal sense to lease unless you change vehicles more often than that.