Excuse the pedantry, but I think this is the incorrect physical explanation. Larger rollers mean that the linear speed at the rim is larger, and the roller impart in fact less force (e.g. conservation of energy).
Does not mean it is less dangerous. It's just dangerous for different reasons than you state.
My thought is the larger roller surface area just made it better at grabbing stuff and sucking it under the unusually high deck height. Dunno if torque is the correct term.
A treadmill design using large rollers would have a chosen motor and gearing combination to accomodate the large rollers, likewise for one with small rollers. They would likely be able to impart the same force at the roller (or at least which one would be stronger is unknown and a function of other design variables).