It was in God's justice that He punished the Canaanite and the Egyptians. If there is any "blame" to be laid in God's acting in the manner He did, look to those who were their leaders, for they are the ones who called down God's wrath upon the people. And it isn't as if He did not give warning and a time for repentance, either. When the "measure of iniquity" is filled, justice needs to be served.

"The Lord saith, 'I think thoughts of peace, and not of affliction: you shall call upon Me, and I will hear you; I will bring back your captivity from all places" Jer 29: 11-12, 14

The real problem today is no one wants to see or believe that there are consequences to actions, and sometimes those consequences affect far more than the those whose actions brought about the end result.

Bringing it down to human level: what do you think about those children who are the innocent victims of abortion or infanticide? Would you call the women who allow it, and the abortionists who perform it "indiscriminate murderers"? I would. For good reasons.