Strategically it has a huge benefit to Apple. Touch ID provides a secure way to authenticate your iTunes account, which millions have linked to their credit cards.
If Apple ever starts offering payment services through iTunes (using NFC or some other technology), authenticated payments can be done in an instant instead of "just wait a bit while I enter my password".
By strategically I mean that while it may offer great benefits to both customers and apple, the technology in and of itself offers only a small barrier to moving to another platform. That barrier will rise with the adoption of touch id across Apple devices and services.
If you're an iPhone user and I took away your iPhone and replaced it with an Android phone, would the first thing you complain about be touch id?
Build quality, accessories, apps (maybe?) are all things that Apple has going for it with the iPhone that at the moment are more strategically important than touch id.
It's like free samples at Costco. They're awesome, you miss them when you shop at a different grocery store, but at the end of the day there are other reasons why you shop at Costco and if you decided you needed to go to a different grocery store, those free samples aren't going to sway you to come back.
If I was used to paying for goods with my iPhone using touch ID and I had to start entering a passphrase instead with another phone to make payments, it might very well be one of the biggest complaints I had.
If Apple ever starts offering payment services through iTunes (using NFC or some other technology), authenticated payments can be done in an instant instead of "just wait a bit while I enter my password".