Most Republicans and even many Democrats would like to overhaul the system in the interest of fairness and efficiency, but that's in fact quite hard, because when you move one piece of the puzzle, another piece, or 15 or 16 other pieces, maybe 200, are affected and require rearranging. The appetite of the U. S. Congress, and of the lobbying industry, for this kind of activity cannot be considered strong. Some adjustments, yes -- we might try a few. But outright overhaul? I think we can believe that when we see it.
Thus the unfairnesses and outrages -- e.g., singling out and stonewalling conservative 501(c)4's when they apply for tax-exempt status -- will go on for a long, long time. Better, more logical and less wasteful modes of taxation, such as the flat-tax -- won't get considered, separately or in combination with other devices for the extraction of money from the customers.
Here we go again: the supposedly simple, putatively constructive measures of generations past - progressive income tax, Social Security, Medicare -- turned not to be so simple or constructive as imagined. That was because they had less to do with efficiency than with Social Uplift -- the movement, by government, of whole populations to plateaus of bliss that only politicians and bureaucrats could see as sustainable in original form.
It all looked good for a while, until the politicians and bureaucrats got carried away with their work: expanding, expending, complexifying just because they could and because there were rich political rewards in doing so.
Thoreau had it right. "That government is best which governs least."