Lack of cargo ships? We have the Hauler and the three Lakons. That's 4 cargo ships.
How many dedicated fighters do we have?
Eagle, Viper (both of which are obsolete now), Vulture and FdL. Also 4.
dedicated explorers, as if there really is such a thing, we just have 2
Where would you place the type 8? Where the Python is? That would make it really hard to compete.
Or closer to the Type 7? That would basically render the Type 7 obsolete, which already has a really rough time holding up against the Clipper.
Here's one thing to keep in mind about cargo ships. Bigger is strictly better. That means once you have the bigger one, all before it are useless to you. You may find yourself downgrading for exploration, combat or mission running. But you'd never downgrade to a Type 7 for trading when you have an Anaconda.