The entire principle behind estate taxes, which are only relevant to those with
significant estates, is to prevent the massive accumulation of wealth by a tiny minority.
The United States, as conceived, was a departure from the European system comprised mostly of wealthy land owners and destitute peasants.
In a sense, the estate tax is an unfortunate necessity. Without it you would have Paris Hilton inheriting billions absolutely tax free, and likely accumulating even more wealth not by any particular skill, but through interest alone. That much money has a sort of gravitational pull at that point if not mis-managed.