It's mostly due to the competition from the "normal" Falcon 9, which is quite capable and could be used for most of the existing payloads. Besides that, curren

It's mostly due to the competition from the "normal" Falcon 9, which is quite capable and could be used for most of the existing payloads. Besides that, currently the payload is limited by the size of the fairing. SpaceX is working on the bigger fairing, but it is not available yet.