It's ridiculous because you've already paid taxes on the accumlation of tangible assets.
For example: you buy a gold coin for a buck. You sell it for two bucks, say, five years later. You have to record that Capital Gain, and pay a tax based on that market exchange. While your buck turned into two bucks (for you), fat Uncle Sam gets to turn around and tax that same asset again, while not giving a tax credit for asset losses.
Suppose, after selling that coin for cash, you want to leave the Legal Tender to your children/heirs. Fat Uncle Sam, in many cases, wants 55 cents on the dollar.
I oversimplified, but you get it.
But that's not much different than most other taxes. Any income I earn gets taxed. And then when I go spend it, it gets taxed again. If I invest it and make money, that gain gets taxed. If I earn money, invest it and realize a gain, then take my gain and spend it on something, it's already been taxed 3 times. Not saying I like it, but I don't get what's so special about an estate tax that it desperately needs cutting. Why is it so much worse than any other tax?
Don't forget though, the gold coin you paid a buck for- you were taxed on THAT buck as well. You may have earned 1.35, but after taxes, you had 1.00 left over.