You're right UGB, not many guitars are optimized in the nut slot area. I guess it's better for the manufacturers to leave them a bit on the high side as it's much easier to make them deeper later on, as fine tuning, than trying to make a slot shallower.
Stangely enough, quite by accident, I wound up with two guitars that have a 'zero-fret'. My Strat, which I bought in '73 in London and had the young tech Seymour Duncan who worked there tweak its action. He had already inset a zero-fret in front of the nut, making open and fretted strings sound the same. Years later I fell in love with a little Gibson nylon string and had to buy it. It's the one I use in some of the lesson movies here ... strangely, it has a a zero-fret too.
I like 'em. I'll take a picture of them ... here you go!
You must, of course, move the nut back. It just becomes a device to keep the strings separate and ceases to be a critical part of the intonation/action. The zero-fret then has to be set where the nut was, the leading edge, to be precise. DON'T DO THIS AT HOME! Not unless you're talented in that area.