IMO construction ships are more or less unnecessary. Aside from four anomalys I can think of, they are only used for construction, which could be handled with much less clicking from the galaxy view (add a button, which when clicked changes into claim/starbase build mode, build resource/mining stations the same way or add a policy for autobuild). Right now the limiting factors for starbase construction are influence and alloys, not constructionship availability, as they don't gather resources or such and can be build very cheaply.