Depends what he/she does with the money. There are many things that government won't do and there is no market for it e.g. Polio vaccine. You have to have wealthy individuals to fund these ideas. Never mind that. You cannot design the system to force people to give you the money. They would move with the capital abroad. What do you do then? Start a war? Wealth is not a problem. Corruption and poverty are.

Or even the recipients: "If my children are competent, they don’t need my money. If they’re not, leaving them a lot of money is only doing them harm."

http://www.theglobeandmail.com/news/world/chinese-philanthro...

Even in our age most of the wealth is in the hands of people who don't own millions, and they're the ones that would really worry about inheritance. If you keep looking at the exceptions to explain the rules, you'll always end up with weird edge cases. The super rich don't need inheritance law, they can use their money to get what they want, even if it's illegal.