Because they are idiots. No one who calls himself "conservative" should support NPV because NPV was never the law of the land when it came to electing Presidents. Ever.
0bama is in serious trouble. The Democrats always throw out NPV as a "solution" to a "problem" (which of course doesn't exist) whenever they need helpful fraud in major cities to negate red state voters.
Unable to agree on any particular method, the Founding Fathers left the choice of method for selecting presidential electors exclusively to the states by adopting the language contained in section 1 of Article II of the U.S. Constitution— “Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors . . .” The U.S. Supreme Court has repeatedly characterized the authority of the state legislatures over the manner of awarding their electoral votes as “plenary” and “exclusive.”
The constitution does not prohibit any of the methods that were debated and rejected. Indeed, a majority of the states appointed their presidential electors using two of the rejected methods in the nation’s first presidential election in 1789 (i.e., appointment by the legislature and by the governor and his cabinet). Presidential electors were appointed by state legislatures for almost a century.
Neither of the two most important features of the current system of electing the President (namely, universal suffrage, and the 48 state-by-state winner-take-all method) are in the U.S. Constitution. Neither was the choice of the Founders when they went back to their states to organize the nation’s first presidential election.
In 1789, in the nation’s first election, the people had no vote for President in most states, only men who owned a substantial amount of property could vote, and only three states used the state-by-state winner-take-all method to award electoral votes.
The current 48 state-by-state winner-take-all method (i.e., awarding all of a state’s electoral votes to the candidate who receives the most popular votes in a particular state) is not entitled to any special deference based on history or the historical meaning of the words in the U.S. Constitution. It is not mentioned in the U.S. Constitution, the debates of the Constitutional Convention, or the Federalist Papers. The actions taken by the Founding Fathers make it clear that they never gave their imprimatur to the winner-take-all method.
The constitutional wording does not encourage, discourage, require, or prohibit the use of any particular method for awarding the state’s electoral votes.