[Why not remove education funding from property taxes completely.]

Most of the states' revenue comes from sales taxes, so the higher % of school district funding that comes from the state level (as opposed to property taxes at the county or local level), the more would be paying for K-12 via sales taxes.

[Instead the state should institute an income tax (weighted on the upper end earners) that pays entirely for the education system in Washington.]

The voters have already rejected such an idea, more than once, and should so AGAIN. This is an especially terrible idea, with the most egregious part being the "tax the rich" Robin-Hood sentiment attached.