Who are you (or Apple, or anyone else, for that matter) to dictate what is, or isn't a legitimate use case for a laptop, or any other device for that matter? New usages are emerging every day, and they have the potential to become as numerous as the neurons in the human brain.
Your position is completely backward. People determine their own needs and desires based upon what they want to do in their lives. If enough people decide that they have a need (or even just a desire) for 1TB or more storage capacity on a laptop or other mobile device, even a smart phone... then that usage will become a new target market very quickly.
Device manufacturers (if they intend to stay in business) will continue to find innovative ways to fulfill the needs and desires of new and emerging target markets. If there is a market for 1TB or greater storage capacities in mobile devices, someone will go after that market and innovate a solution to fulfill that need.
To attempt to dictate what usage models and use cases are "acceptable" for any technology or capability is just about as out-of-touch and blind as Bill Gates was when he said, "640k is all the memory anyone should ever need on a PC".
In today's connected world of immersive media, big data and exponentially increasing processing power, people will continue to consume more and more data, and they will want immediate access to that data no matter where they are or what they are doing.
Look at some of the newest innovations on the market-- USB and Bluetooth video projectors smaller than a pack of cigarettes, that enable you to project HD quality video from a smartphone... that's just one single example. Wearable technology is multiplying as we speak, and emerging into more than just wrist-bound devices.
People will grow their mobile media libraries: because they can. Information at your fingertips (or even in your sunglasses or contacts) is the new techno-lifestyle reality of our time, and it's coming of age very, very quickly.
We can no more resist this than we can keep the sun from rising. And we shouldn't want to.
The secret to long-term success (and even relevance, for that matter) is the ability to nimbly adapt to an ever-changing human culture. Indeed, we must view these changes as opportunities. It is futile to view them any other way. Accept this. Embrace it... or get left in the dust by those who will.
Cheers,
-=Cameron