The Old Testament God certainly 'visited people's sins upon them' - and even upon their children! Now I agree that in many cases this may not have been a direct intervention on His part - He may just have permitted the 'natural' consequences of their sin, or removed His protection from them so that the devil could visit sickness etc. on them. (Indeed, in the case of Job, such a thing happened with no reference to disciplining Job for his sins!) However, at times, the divine initiative seems far more active and direct (as with the examples already quoted) - again, who was it destroyed Sodom and Gomorrah for their sin, or ordered the destruction of the pagan nations in the Promised Land? The OT prophets had no scruples in declaring destruction from God upon His enemies, or, indded, His own rebellious people - eg Jeremiah 19:3ff "Thus saith the Lord of Hosts, the God of Israel; behold I will bring evil upon this place, the which whoever heareth, his ears shall tingle. Because they have forsaken me.. I will cause them to fall by the sword...and I will make this city desolate...I will bring upon this city and upon all her towns the evil that I have pronounced against it, because they have hardened their necks that they might not hear my words." This is, surely, far more than a passive 'permitting' of destruction!
This does appear, at first sight, at odds with the message of Jesus and the New Testament - which led to the Manichean heresy, where the jealous and vengeful Yahweh/Jehovah was seen as a separate and inferior deity to the True God, the loving and merciful Father of Christ. Yet even here we see warnings of how terrible it is to fall into the hands of the Living God. Jesus himself pronounced 'woe' against the Pharisees and others. Ultimately, most of us believe that unrepentant sinners will be punished in Hell - which is a far more drastic thing than a temporary illness, or even physical death - indeed, Paul advocated the handing over of hardened sinners to Satan for the destruction of their flesh, so that their souls might be saved in the day of judgement.
Throughout the Bible it is clear that 'the wrath of God is kindled' against sin and those who cling to it (often in very graphic ways) - therefore, in His mercy, Christ came to take that wrath upon Himself and turn aside the punishment which was due to us. Were there no divine wrath and no consequent punishment, there would have been no atonement to be made!
Anthony