the worst (and usually the stupidest) situation is, if a freighter (from a trade fleet you outnumber 3:1) comes "back alive" and the marines fail and it gets away... he gets away with his cargo WTF from a military force they just kicked the *** out of his fleet.
Well, you did choose for your ships to not engage the survivor, and you did choose to put your own forces in the way if you suddenly needed to engage the target. And what do you expect them to do with the cargo? Dump it out of the loading hatch? They've been working hard to restore power to enough of the ship's systems to get underway since they were disabled, they need the money those goods can buy them if they manage to escape, and dumping the stuff takes time that they probably didn't have to spare. And then you went ahead and gave them a perfect opportunity to run by launching a bunch of boarding pods that interfere with your fleet's ability to engage their ship without killing your own marines or crewmen.
The portion of your fleet that you didn't task to participate in the boarding operations is probably busy with the salvage operations anyways, and there's no reason to think that this occupation leaves your ships in excellent position to interdict an escaping freighter, especially when you told them to ignore it by choosing to not have those vessels participate in the boarding action. Those ships which you did choose to have participate in the boarding action have a bunch of boarding pods obscuring their target and preventing them from getting a good shot without risking hitting friendlies, and since you chose the boarding pods option rather than hard docking, the ships are holding off at a distance anyways.
Admiral Piett felt the same way 
That hyperdrive was down!
I think that right around when the Falcon escaped, the recently promoted Admiral was more concerned with what Vader was doing and with whether or not he'd just earned the distinction of being Vader's shortest-lived immediate subordinate than with how unfair it is that the freighter got away.
The whole self-destruct mechanic is a crutch - totally wasted ship without power somehow self-destructs. I can understand crew sabotaged all systems beyond repair but self-destruct in already dead vessel.
But the ship isn't without power, is it? After all, that's what brought it to your attention - the ship's systems came back to life, and that's what attracted your attention and suggested that the ship might be worth boarding in the first place.
