I'm not entirely certain that that's valid -- in my own opinion, of course.
"Old money" will always be around, but when people have worked hard to amass that fortune then what further claim should be had upon it? It was taxed in the beginning, so why should it be further chipped on as the years move on?
If I were mega-rich, through my own legitimate toils and tax paying, I'd like to think that the money is mine to do whatever I wish with. Even if that means passing it on when I die without further interference. That seems perfectly reasonable to me.
I'm interested in knowing your opinions on that.
In brief, my opinion is something like this;
If we accept taxation is inevitable (it is), then we should collect it in such a way that hardship on those clobbered with it is minimised.
I see few better ways of doing that than, effectively, taxing people who are about to receive very large amounts of cash which they have contributed nothing toward earning. It doesn't make the will beneficiary worse off than before the transaction, since they are still receiving a lot of unearned money. There seems a lot of fairness in that, to me.