What is the source of your data? According to the world bank and the OECD, from 1986 to now the income share held by the top 10% has been in a range from 27 - 31%.
http://data.worldbank.org/indicator/SI.DST.10TH.10?locations...
http://www.oecd.org/els/soc/growingunequalincomedistribution...
>...Further, the top marginal tax rate has little to do with the top 10% of all incomes.
As I have tried to explain in the previous comment, the top marginal rate means very little.
>...Yes, in theory they where a bad idea. However, in practice they seem to have been a net benefit.
In reality, they were a bad idea. It should be a hint that you don't see mainstream economists suggesting we return to them. Politicians find them a good talking point since everyone likes the idea of someone else paying more taxes, but you don't see economists suggesting it.
>...Either though reducing the rent seeking behavior of capital, or alternatively because the middle class's spending is mass producible. (You can scale iPhones, you can't scale 50,000+$ watches because they are not intended to be scaled.)
How exactly does a confiscatory rate reduce the rent seeking behavior of capital - that seems like a different issue. In reality, high rates encourage money to be spent in non-productive ways to influence congress to carve out special tax deductions/credits. Enough loopholes were in the old tax code that some politically well connected wealthy people sometimes paid no taxes - this is why the AMT was created.