I don't think this TV is meant to come out in that size just yet. 65" was the max size for now. The 75" wont be till much later (September or later.) Amazon only lists the TVs that come in the near future/that they can let people pre-order.
This is last years model. The price reflects that with a ~50% reduction from last years retail price. This years new model should be out in May. You don't need to use all the features but it is nice to have the option.