Where do dead people spend their money?
Doesn't matter. That money is theirs to do with what they will. It has already been taxed enough.
You do realize that the death tax is one of the biggest killer of small businesses don't you? A person whose business might be worth millions does not necessarily produce enough income to offset the death tax. For example a dairy business where there is a lot of land value but relatively little income in comparison. People would not be able to leave this business in the family because the fucking government wants to take 55% of the value.
So the message from the government is, "Don't expect to be able to pass your business on to your progeny because we're going to steal it out from under you"