Good points: floor height and axle durability... but I remember riding in my father's 31 (?) foot Sovereign
trailer growing up, and the ride was rough!
I remember the cabinets shaking 'til I thought they'd drop off the walls. And literally seeing the torsional forces twist the shell.
An indy suspension would help ride considerably, and help keep the trailer tight and rattle free (well, almost rattle free).
Plus, you could add electronically actuated steering to those wheels, too, at a weight penalty of about 250 pounds or so. This would help freeway lane-changing stability, as well as low-speed manuverability.
I'm still convinced an indy suspension is a better idea.