In this situation, it is very difficult to have an AI that can come close to matching a human player. It is difficult to teach an AI what an 'important' star system is outside of the value of the worlds in it. With starlanes, though, you actually have geography, in a sense; there may only be three 'entrances' to your Empire, and so the AI sees this as a border, as a front line; it can also plan an actual attack strategy and say things like 'I am going to attack his mining world, and to do that I must get past points A and B, so I will garrison point B with a small force and move on to point A through starlane X.'
Much of what I know about the challenges of AI programming does not come from my being an AI programmer (I'm not) but from watching the development of EU2, HoI, and Victoria, all of which have enormous challenges with AI. The distinctions they use tend to be along the lines of 'the eastern front' or 'guard the northern coast of France.' The more we can distinguish the map, the more the AI can work with it.
That's one of many reasons why I recommended to implement sectors thing. It is useful even just as a programming tool.
If you feel like it, please share your opinions! I'm quite dead against it but there could be things I've overlooked, naturally.
-Imagine a starlane that links your homeworld to the backwaters of another empire. All of sudden, those two linked system becomes a huge strategic spots. Just imagine space treches and mountains; just as you go through valleys and flat plains instead of over a mountain, a starlane speeds up your trip too in space.
-Imagine a cluster of connected systems. Just imagine how easily to defend those cluster because your ships can move back and forth from back lines to front lines in an instant. That region of system has logistic benefits for your military.
-Or how about a system with a bunch of one-way starlanes that connects to all parts of the galaxy. Who ever controls that system sure got some power. Imagine you can launch fleets to whoever at will in one turn and will take them 10 turns to respond with an counter.
-Starlanes can be used to nerf overpowered rich planets. By making rich systems have a lot of starlanes going into them, the system becomes harder to protect and make the game more balanced.
-Starlanes is a good excuse to put flashy lines to spice up the graphics.
If we implement starlanes correctly, it should enrich the game. By proper, I don't mean moo3 starlanes cuz that system was stupid. I think its biggest mistake in starlane department is having all systems connected by one or more starlanes.
On another note, ppl have suggested to add "mountains" and other specials to the galaxy map as well as to the tatical space combat map. Special regions like nebula or black hole may have some gameplay effects.