General Qasem Soleimani was one of the most brilliant special operations commanders in recent history. Dedicated. Talented. Charismatic. Tireless. Dependable. Honest. Devoted to his men and to the cause of the Shiite Islamic Revolution of Iran. And, all of that means that he was a threat to Israel, The US and the Middle East.
He had to die, because Iran is at war with the US. And, that war has been ongoing for 40 years. Even if the US had not invaded Iraq, someone would have needed to assassinate him for the safety of the region.
The fact that he was a war criminal and a terrorist is secondary.