Thank you for a very intelligent analysis of Leasing and Financing. I've been a very keen advocate of leasing for some time.

Important - Keep in mind
You also need to really understand residual values when you compare leasing to financing. As you stated, the Bank (or credit facility) guarantees the residual at the end of the term. In a finance, you are on the hook if ever you want to sell/trade in the car. If the car's value drops for whatever reason, the Finance customer is left holding the bill.

In my case, my lease is coming due in June. The residual is CAD$26,500, but actual wholesale value is $CAD$22,000. If I would have purchased the car and financed it, I would stand to lose an additional $4500 in depreciation if I chose to trade-in the car... in the leasing scenario, BMW Finance will take the $4500 hit.

If the reverse were true (ie. residual is lower than wholesale/market value), you could buy out the lease and trade it in (or sell it privately)

Finance = More Risk
Lease = Low Risk -> Finance company assumes the risk