I may have a misunderstanding of trade routes in Sins1 and if so, please correct me. My understanding is you get a bonus for a longer trade route, but the shortest possible route between ports is used to determine the longest route. So, if you visualize a dozen planets connected in a circle, you'd want one of them to NOT have a trade port because the longest route would be 10; if all planets in this circle had a trade port, the longest route would be 1.
Is that changing in Sins II? It seems like trade would benefit from a higher number of connected worlds to a trade route, so in other words, the longest possible contiguous path between two planets.