[bhahn]

Then why didn’t they?

I would give them some benefit of the doubt to one of the biggest companies in the world that they had at least a dozen people research this and came to the conclusion that they couldn’t or didn’t want to (due to cost, design, etc).

[mantap]

The same reason that Apple shipped broken keyboards with MacBooks for years. Because Tim Cook is not a product person. He is an operations person. Adding a fingerprint sensor is good for the product but bad for operations. Who do you think he's going to side with?

At the risk of using a cliche, I think Jobs would have made a different decision.

[willis936]

The answer seems obvious: they are pigheadedly stubborn when it comes to design decisions. They will never throw away a design decision within 5 years because that would be admitting they made a sub-optimal decision at some point. It simply is not on brand.