I don't know any Christian who thinks that particular punishment would be good idea today. As said before, New Covenant <> Mosaic Laws.
The Israelites were a fickle bunch in the beginning, ready to worship a golden calf as Moses disappeared for two minutes. The temptation to mix their faith and worship with the pagan worship around them was real. Even Moses was wavering near the end, disrespecting God during the journey to Promised Land. The Mosaic Law was written in a way so that the Israelites would have a severe respect for principles of God's principles (respecting parents, respecting other's property, respect other people). If during that time, the punishments had been light, the logical consequence during that historical time period would been that Israel would have dissolved and been absorbed by neighboring pagan countries. Nobody would have had respect for anything if punishments had been light. It's a consequence of a kingdom with a juvenile mentality. You have to punish a child even when he does not yet understand why he's being punished.
God needed to create the foundation...the respect for those principles (respect for others, no stealing, no cursing) before Jesus, who would provide mercy, grace, and forgiveness to arrive. If Jesus had come without Isreal's kingdom established and the principles in place, nobody around Him would have understood what He was trying to do. It would have been completely out of mind, nonsense to them. Reverence for those principles was needed before grace and mercy could be provided. Otherwise people would have just taken those principles for granted.
When you read the Bible, you have to understand history, context, how the covenants apply, and the purpose of God throughout is applied. You can't cherry pick a verse and close the Bible. Nobody does that for any other piece of literature.