To quote The Simpsons: "You don't win friends with salad". That is to say, Republicans don't win voters with well-thought-out tax restructuring plans, they win them with "God, Guns and Gays" policies that appeal the the lowest common denominator.
It's like a vicious cycle: they chase the LCD voters, who are typically less educated, and as a side-effect in the policies of the GOP, they vote down more educational spending, creating more less-educated voters who respond to these vacuous non-issues, and so on.
If you look at the voting statistics, majority of uneducated and lightly educated (high school only) votes Democrat. College graduates lean Republican, while higher degrees (academia) leans Democrat. So it would be counterproductive for Republicans to have more less-educated voters, since those prefer Democrats.
Education spending is another red herring - public schools spend no less and sometimes more than private schools, costs of K12 education per pupil tripled since 70s with little to no improvement in any measurable metrics, teacher employment has grown faster than enrollment for 40 years now.