Really? Congress decided for a long time that foreign women who married American men would automatically become US citizens without having to be naturalized. If they hadn't done that, "birthers" would have contested whether Woodrow Wilson or Herbert Hoover could actually become president. By changing the rules on citizenship, Congress arguably moved some cases from one category to another, thus having an effect on what the Constitution meant.
If you think that foreign women who marry American men automatically become U.S citizens without having to be naturalized, you’re even further behind the eight-ball here than I might’ve thought. I married a foreign woman who NATURALIZED as an American citizen several years later.
Congress was explicitly granted the power in the Constitution to determine the rules for immigration and naturalization. No such power was granted to determine natural born citizenship.