Why does Jesus not want people to repent and be forgiven in Mark 4? This is in response to the disciples asking why Jesus teaches in parables:


  He said to them, "The secret of the kingdom of God has been given to you. But to those outside, everything is in parables, so that although they look they may look but not see, and although they hear they may hear but not understand, so they may not repent and be forgiven." -Mark 4:11-12 New English Translation


Why does he say this? Why is he teaching at all if his intent is actually that the people not see, not understand, and not repent. It seems troubling.
Your Bible is missing the double quotes.  Jesus is quoting Isaiah: 


  Then I heard the voice of the Lord saying, “Whom shall I send? Who will go for us?” “Here I am,” I said; “send me!” And he replied: Go and say to this people:
  Listen carefully, but do not understand!
  Look intently, but do not perceive!
  Make the heart of this people sluggish,
  dull their ears and close their eyes;
  Lest they see with their eyes, and hear with their ears,
  and their heart understand,
  and they turn and be healed.


Isaiah 6:8-10 (NABRE)

I think He's describing the process shown in the OT and exemplified throughout human history, not issuing a command.

According to the intratext in the NABRE, this is also quoted in 

John 12:40; Acts 28:26; and Romans 11:8.

I can't say that I particularly understand the meaning of Jesus' words, but hopefully it'll point you in the right direction.