What solution is there for users who need lots of (> 1 TB) storage in a MacBook Pro?
The wireless networking on Apple hardware is really as fast as spinning hard drives can shove data so there's not much benefit to putting large storage in a device as I see it.

We run the MacBook pro in places where an iMac used to be needed with iSCSI initiators to connect to SAN, AFP and SMB shares to file servers, thunderbolt and USB 3.0 access to drives.

If you benchmark the speed of the SSD in that hardware, you'll see why it's so pricey. If you think of that as fast cache - high speed storage premium tier and then look at your workload - you can think about how you can place low access speed requirements and long term storage elsewhere and let the system cache the files needed locally.

Apple is going that way for iCloud, Photos, iTunes - having a large library and letting the system go out to the cloud as needed to retrieve files. If that change doesn't arrive at a pace you like or you really need to bring several TB of storage with you - there are great options with thunderbolt and USB 3 as well as networked storage to fit many sizes and price points.