According to the news, what is the main advantage of the digital key?

Got a smartphone? Never lose your hotel key, or even have to stop at the registration desk again. That’s the vision of a hotel chain that plans to send digital keys to guests’ phones via an app instead of making them check in and get the traditional plastic swipe cards.(23)Arriving guests could bypass the front desk and go straight to their rooms.(24)Starwood Hotels & Resorts, which owns more than 1,150 hotels in nearly 100 countries, plans to install the system in the next three months at two of its hotels in the U. S. A. If all goes well, the company says it could have the feature in all of its hotels by next year. A spokeswoman said the app will initially be compatible with recent iPhone models(4S and newer)and newer Android phones. The app will use Bluetooth technology to unlock the room with a tap.