I realize this question is contrived, but I figure it might provoke some fun discussion, so here goes:
If you could push a button and have your brain modified to precisely remove a cognitive bias (and have no other unnecessary effects—most convenient possible world), which would you choose? Why?
What if you were choosing for the whole human race?
Well, clearly the question of whether someone got the necessary education about the dangers of AIDS stops being a problem when you're willing to just assume they know everything they should need to know. This might be a reasonable assumption in the first world, if you also assume the vast majority of people with AIDS actually did get it from risky activities instead of just things like being born to a parent who was HIV-positive, I'm not sure what the actual statistics are on that.