This is an end-run around the Constitution. In order to have the system you suggest, the Constitution would have to be amended. In effect, it is undermining the concept of federalism.
I’m surprised someone hasn’t taken this all the way to the Supreme Court. They would definitely rule against it.
There is nothing in the Constitution mandating a popular vote.
Article II, Section 1:
Each State shall appoint, in such Manner as the Legislature thereof may direct, a Number of Electors, equal to the whole Number of Senators and Representatives to which the State may be entitled in the Congress: but no Senator or Representative, or Person holding an Office of Trust or Profit under the United States, shall be appointed an Elector.If the state legislature chose to, it could take the presidential election off the Nov 4 ballot entirely, and decide who the state's electoral vote goes to by legislation