Forget the demo. SOTS already had 2 expansion, each bringing in a LOT Of new stuff and many, many changes.
The one ship running way was probably the command ship. Everybody was doing it (playesr too), so the AI was smart enough to keep the command ship out of harms way too. It's simple enough to counter.
A little hint -- autoresolve uses close range for battle calculations - in other words, if you have ships with strong close combat weapons, you stand much better chahges in autoresolve. Autoresolve also uses your reinforcement list and current fleet setup, so it can f*** you up if you're not careful (not surprising).
That said, the expansions changed much. Reinforcements spawn near the command ship now, so neither the player nor the AI will run away with it anymore.
Trade and diplomacy both got huge boosts. A new research tree was added (Xenotech), 2 new races, drones, lots of new sections, techs and weapons and a whole load of improvements and modifications.
Seriously, SOTS is a game that grows with each PATCH (seriously, the devs' keep improving it and cramming the patches with lots of stuff, so every patch is greeted as a mini-expansuion initself)