“cleverness” comes to mind as a better substitute
Or “Hubris”. In the examples, the people go wrong not because they are using reason and they should not use reason, but because they falsely imagine they are capable of using reason sufficiently to deal with the particular issue.
I think the meaning is, that on reading something unpalatable, one may be tempted to write it off as “crazy” or “stupid” quickly, and then ignore it, and trying to see the good in it may be more useful; and calling the writer crazy or stupid will make further communication more difficult. So when someone uses those words too readily, that person is called “mean”, and seen as not “nice”.