Should anyone be taxed, ever, then?
The government is just like a business or a household. It has expenses. It must have income. After that it is just a case of deciding how best to get that income. Conservatives believe that borrowing is the best way to do that. Liberals believe that the income should come from the citizens who benefit from the services provided.
The estate tax (which isn't all that high, but it applies to large amounts of cash every year) is about as fair as any way to raise cash that I can think of. The person whose cash it was, is dead, after all.