>Instead, we should make it illegal to discriminate based on criminal conviction history

Absolutely not. I'm not saying every crime should disqualify you from every job but convictions are really a government officialized account of your behavior. Knowing a person has trouble controlling their impulses leading to aggrevated assault or something very much tells you they won't be good for certain roles. As a business you are liable for what your employees do it's in both your interests and your customers interests not to create dangerous situations.