That is actually how SS was set up to work, intentional or not. When it started the average retirement age was 65 and I believe the average life expectancy was around 67. The program is in dire straights because retirees are drawing benefits far longer than was ever planned. Bring the life expectancy from the 80's back to the 60's and the problem will solve itself. For some reason that doesn't seem to be a popular political solution.
There are a lot of people in your 70% that would benefit from itemized deductions. My guess is that, as often as not, they don't take them because they are intimidated by the tax code. If you really look at the deductions that can be taken they overwhelmingly favor middle income earners and small businesses. Look at something like a home office deduction. I take one every year and I bet Warren Buffett does, too. That savings of a few thousand dollars means a great deal more to me than it does to him.