I'm making this suggestion because I think there would be a good balance (and because I'm quite selfish ;)) for visibility.
Anyways, here's what I propose: a new visibility option that highlights the entire planned path that packets will take.
This is different from the default visibility in that the default visibility only shows the the connections the packet took so far (before reaching the destination), as opposed to showing the entire planned path of the packet.
The reason I'd like this is that more units would get built as time goes on, but "All Paths" would make things hard to see, and the default visibility wouldn't show that something isn't connected.
Apologies if this was hard to understand, my English isn't the best :-[
You've been very clear, actually.
This sounds interesting, but I understand that the network-crawl algorithm is quite expensive (laggy) to run. That's why paths are "pinged" by packets on them to show up, rather than showing the planner route.
The term for what you're hoping to see is "minimum spanning tree", and I'm quite sure knucracker has considered it. Problems come in with things like "what if you have a [limited-supply-pod/microrift/soon-to-be-built-connection]?".
The fundamental question is generally one of lag, though. If there's a good way to solve that, I think this would indeed be very useful.