From statements that have come out since the trial, I suspect that the jurors were simply punishing Samsung for "copying" Apple, which there's pretty blatant evidence that they did. (Whether or not there's anything *wrong* with copying something wholesale, it does tend to "feel wrong" to most people).
I doubt a single person in that room took the time to debate the deeper issues of prior art, and the triviality of the patents themselves. In fact, one juror almost admitted as much: "we were debating about the prior art [...] In fact we skipped that one," Ilagan continued, "so we could go on faster."
To my mind, the issues of prior art and the patentability of look-and-feel were not at all addressed by this trial, because the copying was so blatant that it obscured the more important issues.