Spam causes most networked companies thousands of dollars a year. I work in IT and know from experience that spam will clog a network to a stand still or maybe it will just crash a mail server. This causes companies to lose money, spend countless hours trying to fix and block the spammers. There are so many reasons spammers are bad. What about morally wrong? Some may consider this a violation of privacy as well.
Now back in the day I did a little spamming myself so I know the profits in spamming which is why it will never go away.