I disagree. What turns many states into "Blue" states is high Dem voting in major cities (often accompanied with vote fraud). Doing this would mean that the Dems would only get the electoral votes of the big cities' congressional districts, and the rest of the state would likely go R.
Allocating the electoral votes by district within a state removes the incentive to cheat in the areas where its common. Democrats, unions, etc will figure out pretty quickly that wasting money on vote fraud is a pure loser.