AMT + Deduction Cap would be the same thing effectively, assuming the deduction cap applied to everything. Right now the reason people make millions and pay no taxes is because they give generously to charities, and their investments are tax-free muni bonds. AMT still allows too many deductions to force all the top earners into paying taxes.

The big deal is that AMT doesn't apply to capital gains (at least not directly; it can cause you to blow the exemption cap though)

I suppose my point is that we have a feature in the tax code which is ostensibly designed to achieve his very goals, but it's become useless over time because a) it's not indexed to inflation, and b) it allows some deductions and generally adds complexity, rather than being a true flat minimum.