While criticism of the ending is welcome (especially on first playthrough!), you're wrong on a few counts.
1) The GTVA had certainly sent probes into the system. In all likelihood it also sent SOC teams to do physical scouting and eavesdrop on transmissions.
2) The Renjian's jump drives hadn't had time to recharge. In any case, the ship's captain must have known they were doomed and simply decided to go down fighting.
3) You need to turn the difficulty up; low difficulty handicaps friendly beams.
I'm not a member of the BP team in any creative capacity; I just handle voice acting. Darius, who does all the creative stuff, is very happy to get feedback. However, the first point has been oft debated here, and the last two are just misunderstandings/technical problems on your end.
To be honest, I remember feeling the same kind of shock the first time I played through. "That didn't make sense," I thought. "How contrived!"
But the more times I've replayed AoA, the more I've realized how closely it fits with the themes of the campaign. It's foreshadowed time and again, and more importantly, it sets up what looks like a truly epic sequel.
