The CNK Avenger was designed as a light duty 'short hop' transport. It was built by CNK as a 'budget friendly platform' upon which to build a ship 'tailored to your needs'. They pushed the idea that they would start with the space frame and build it exactly to your specifications 'at no extra charge'. Most people didn't want the level of customization they were offering, so they picked one of the 'starter bundles' and just bought that.
Despite the horrid reputations most CNK ships have, the Avenger proved quite popular. It wasn't the most impressive ship you could buy, and it certainly wasn't 'budget friendly', but they proved very reliable and decently tough in their stock configurations.
Only one customer ever actually took CNK up on their offer of 'free' customization, before the offer was ended. That person was [Lizbeth Locke][], when she ordered her completely custom, heavily armored, not civilian legal variant. It estimated that CNK lost millions on the deal, given her exacting standards and various demands.
However, the Ex Nihilo is still considered by most CNK Institute members to be one of their greatest achievements. It's still used in CNK promotional material to this day.
CNK designed the Avenger to be an easy to modify ship. They took the modularity of the Terrans as an inspiration, but tried to keep that modularity on the inside of the ship rather than the outside. They wanted most Avengers to be identifiable as their base class, while having the internals completely custom to ever purchaser.
This class of ship was made just to have a basis for the Ex Nihilo.