Earlier quoted context omitted.
Perhaps it all comes down to whether you have faith in the American diplomatic corps. If you do, this doesn't make sense. If you don't, it does.
It's not a matter of faith; one generally wouldn't leak mundane information, only proof of misdeeds. And yet much of this leak is pretty mundane, with barely a scandal to be found in the whole thing.
Perhaps that's what makes it rather hard to judge. It's almost a higher-order leak (more words and potential relationships, than actions). So sidestepping all the philosophical dualities at work here (Stewart Brand's free/expensive information, the competing 'dishonesties' of releasing diplomacy at work / diplomats keeping secrets), the fact that we don't have a clear idea about what the resulting actions will be -- makes it even harder to judge. A whistleblower exposing something with a clear resultant action (some guy immediately going to jail, e.g.) is much easier to judge. Given the exponential potential routes all this information could go, it seems almost impossible to make sense of whether releasing it is right or wrong.