C Corporatrions enjoy benefits for their shareholders that are worth more (in some cases) than the 15% cap gains and special dividends rates. The reasons for the double taxation is in part- 1) the corporate shield from unlimited legal liability 2) perpetuity 3) ease of transfer of ownership and aggregation of ownership, 4) a uniform unit of account / method of exchange / store of value.
Legal system in place to oversee these rights and privileges.
Perpetuity only has "value" in light of the death tax. An "S" corporation also shields shareholders from unlimited liability. Any contract, like a real estate trust, also allows trasfer and aggregation of ownership.
"C" corporations are not that special that the government can legitimately hit their shareholders for a double dip.