The difference between a closed drydock and an open spacedock was massive.
The former offered a completely closed environment. Shipbuilding crews gained access to a lot of conveniences. The entire point of building a ship in an enclosed space was to exert as much control as possible.
A drydock also offered plenty of privacy, which was important for building or assembling strategically-important vessels.
The Ovenbird's internal drydock was incredibly valuable to the Larkinson Clan. Being able to service starships at the start was already valuable enough, but that was not the extent of her capabilities. As long as she received some comprehensive upgrades to her drydock facilities, the Larkinson Clan gained the ability to build its own starships!