I think the few logistics slots available is a good thing. It forces you to actually expand and not just turtle at a few planets. If you could just load up on the research centers, and reseource acquiring upgrades on one planet then there is little point to making yourself vulverable by expanding. As the game stands right now, you can stock up on research centres at your home base (to a small degree), but it would mean that you did not spend the resources on ships to capture new areas and you put yourself at a disadvantage by having less in the long run. RTS games generally are all about resources. You just need a military to maximize your reousources. If you don't need to expand militarily (by capturing new planets and the like) then there are less factors being balanced and the game is not as much fun.
What might make things interesting though is having bonus to certain types of logistics buildings. For example, in some sectors make it so that research centres, trade centres, or refineries take up less slots or make it so that they are in some other way more effective.