The AI still does weird stuff at times. Since the AI never moves it's home planet, it should defend it to the death. Bombing planets usually gets the AI to respond, but if their fleet is too weak they simply turn back around and wait at the next gravity well for reinforcements. Meanwhile I'm busy tearing stuff up and moving to the next target. By keeping a large fleet at major chokepoints, and having a small smattering of defenders at areas where the AI sneaks in siege frigates(an amazing waste of resources for the AI, who should be waiting until it can mass 6-10 of them together and only attacking with an escort fleet of other frigates) ensures that your planets are 100% safeguarded. Hell, a single hanger packed with fighters is more than enough to keep all the siege frigates at bay. I'd rather siege frigates be cheaper in both cost and supply while being easier to kill. The pirates are evidence enough that massed siege with escort can mess up a colony, but the regular AI doesn't try to mimic this success. The AI also focuses too much on capital ships, going for the long haul. I'd love to see an AI that changes its strategy to match the size of the map.
That said, you can still get a fair amount of fun out of a one player game if you use maps with 3, 6, or 9 AI players. The Hard AI will build its own massive fleets and actively push outward with them, looking for territory that it can seize or raze. This gives the TEC player a big advantage, since sensor probes give them huge amounts of intel about the map(as if they need a helping hand

). If you learn to use and love the planet info rings, TEC players have knowledge allowing them to dominate and control maps against the AI without breaking a sweat.
Don't get me wrong, I'm glad the Sins AI doesn't cheat like Starcraft AI. Sins AI actually actively scouts an area before advancing, and won't just psychically zero in all of its forces on your weakest spot. But this also has the side effect of making the AI even easier to predict. For example, if you see a light assault frigate pop into your system, and then turn back around, there is an extremely high possibility that the AI has a fleet waiting at the next gravity well. If you don't have defenders there, the AI will advance.
The Unfair difficulty helps address this 'fear of loss' by giving the AI more of everything to work with, leaving you to decide how to best tackle superior numbers, and slowing your expansion. In some ways the very same point-line map structure that makes multiplayer games of Sins fit well in the management scheme of things acts as a roadblock to the AI. But I'd rather play Sins than a game where the AI 'wins' simply because your clicks-per-minute weren't fast enough to keep up with the instant calculations and build orders of the AI, as you find in other RTS games. The Sins system is more elegant as a concept, even if the core gameplay is a bit easier. But if you have the option to adjust its level of cheating when it comes to resource income rates... you can produce a monster!