Because if they're capable of making plenty of good 4-cores but have more demand for 2-cores so are cutting good 4c, they should just make the 4-cores a little cheaper. But maybe they already do this.

Anyways, agreed ECC should be standard, but it requires an extra die and most people can do fine without it, so it probably won't happen. But an ECC CPU option with clearly marketed consumer full ECC RAM would be nice. DDR5 is a nice step in this direction but isn't "full" ECC.

I don't know if mobile cores factor into the same process, but if you have a lot of demand for 2 core system for cheap laptops that can't supply the power or cooling for a 4 core then having more 4 cores, even if they're cheaper doesn't help.