Samson was a womanizer. David was an adulterer and a murderer by proxy. Rahab, a woman in Jesus' genealogy, was a whore. Gideon was a doubting coward. Peter denied knowing Jesus three times in a brief period. Paul was also a murderer of many.
GOD has a way of bringing out the best in the worst of us.
And the reason that GOD chose the name Israel? Because He could. There is not unanimity about its meaning, but most likely it centers around "GOD rules".