I guess where you come down on the estate tax issue depends on whether you prefer a plutocracy or a meritocracy. A hypothetical:
Citizen A is born to poverty. He is the child of a rural Appalachian family which has worked on the factory floor for generations. He has no prospect of inheriting any wealth. He is intelligent, hard-working and honest.
Citizen B is born to wealth. He is, frankly, a dim bulb. Luckily for B, he stands to inherit a fortune upon the demise of his father. He’ll keep that wealth, because in spite of his own lack of talent or intelligence, he has good investment advisors. He will never go hungry, and will never work a day in his life unless it suits his fancy.
Now, why should Citizen B get such an enormous head start in life just because he was lucky enough, by accident of birth, to inherit a fortune. Wouldn’t it be a better system if both A and B started on equal footing, and then rose as high as their own talents and drive could take them?
I would not object to a 100% estate tax. Let each generation earn their own wealth. Seems like such a system would provide a much stronger incentive for personal achievement. As it is, the children of wealth who do have talent and brains may never feel the need to use them, and thus, their potential contributions to society may be lost.