The way the Enterprise blows up has always kind of bothered me. You have the Bridge detonate, then the partial collapse and detonation of the saucer section, then a slow fiery descent into the atmosphere. (Providing a great shot for the movie, which I understand is the actual reason for the sequence, as well a good analogy to how a seafaring ship would sink if scuttled)
However, if that is the way the auto-destruct was supposed to function, wouldn't that potentially leave a partial hulk for for enemies to scavenge if there wasn't a planet nearby to fall into?
It make sense to believe that the sequence at least partially failed due to the existing battle damage doesn't it?