One of the most annoying features for me is the constant need to build constructors. I suppose the idea, as designed, is that the constructor uses itself for the parts in building, but this is counter-intuitive, IMHO.
I would have preferred a system that would incorporate a contructor-module upgrade [considering the bloated nature of the tech tree, what's a few more...
]. Each constructor module is capable of a certain amount of work...the better the module, the more work that can be done within a specified time. Once a module's capacity is exhausted, the constructor has to return to a starbase to get "recharged". A maintenance cost would apply, of course, as well as a vulnerability to attack unless defended by warships.
I can't tell you how boring it is to send a horde of constructors to a starbase site just to get it up and running, especially in a war-zone........