Previously discussed here.
Before current world (w14) ships gained speed as their quality increased.
Every ship having same speed is a good thing. Barring technical issues or gross incompetence, the helmsman of the higher quality ship would always win in a scenario where one ship chases another.
However since the base speed was not changed, everyone who makes a ship higher than q0 has effectively been hit with ship speed nerf that adds up when traveling long distances.
Knarr speed used to be 4-8 units. Why not make it 6 now?