The claustrophobia problem exists even now in widebodies, big deal, make the damned thing smaller. Why should all concepts have to be the size of a football field? Don't tell me about specifics, every plane is thought up with a target agenda in mind, the one of the original reasons for the BWB was that we cannot keep increasing the size of the traditional based design for future high densities. A plane twice the size of an A380 would prove inefficient as an A380-sized wing with twice the payload. I think the biggest problem is how to pressurize a hockey puck with wings.
Reversing square-cube, a smaller BWB (not really a flying wing, don't confuse them) may have an advantage over a medium sized airliner, it surprises me no one has looked into this.
Think of a single class layout for the purposes of clairity, where as you enter the plane there are 6 seats and one aisle and as you go to the back, it becomes 10 seat abreast with two aisles. Maybe it will hold 200 pax and be no bigger than a 739 with twice or more the range because of twice or more the wing area/volume. It would be a high-wing, btw.
No claustrophobia, unless you don't like being in between two aisles...
The meaning of life is curiosity; we were put on this planet to explore opportunities.