Because that same lack of empathy for other people, together with a lack of self control also affects other parts of their life. If that's the kind of person they are then people have a right to now that and judge them for it, because they are likely to do it again.

It doesn't mean never hire them, but it does mean don't put them in a position where they have a larger ability to hurt others.

Obviously some crimes are of the "stupid teen" variety, and other motivations - those should be categorized differently.