Aw shucks. No, do NOT ignore. We should never forget the viciousness of the best of us -- which, when true religion and power combined gave us the crucifixion.
But don't let's leave out the other ones, the ones like Bartolome de las Casas (O.P., koff koff) and those who used whatever they had to protect indigenous peoples and to work against slavery. Wheat AND tares together until the harvest.
What will the Lord of the harvest say when, having already said that wheat and tares should grow together, he hears his workers mocking his field for all the tares in it? Will he not say, "Well, I see the enemy got YOUR attention, and you pay more mind to his interference than to my word."
Well, "focusing on" may be a bit much, but we should never be complacent to live in the midst of sin. We are taught that sin needs correction. If no one ever says anything then sin will just continue to grow in any organization. As with anyone I can think of around here, if you were a member of a group that was fine for a while, but then started to stand for or do very unChristian things, you would work to correct the problem and/or resign from the group. In hyperbole, if the Pope declared today that historic American-style slavery was suddenly fine and dandy, I doubt you would sit idly by and just "go with it". :)
PLUS, we have the whole history of the Church in dealing with heretics, myself included. :)