There should be no slider for stupid, if people want to play "solo" then they can go play ED.
Nope it was sold as having it, whilst CR himself could scrap it there would be an outcry. Bare in mine ED doesn't really have a solo mode either, it's more an online but mostly offline mode, yeah no other players but you still have the impact of players on trade etc.
The way CIG are working it is very reminiscent of Ultima Online, it was essentially a PVP game until they released a patch which essentially created a carbon copy of the world but with tons of artificial rules in it that helped protect people, it was essentially a care-bear version of the same world and people flocked to it. However many stayed in the pvp area, preferring the added danger and opportunities it gave, despite staying there I was rarely attacked but I was still able to take advantage if someone died nearby or was horribly injured.. you know, I'm an opportunist lol .. he had a gun damn it!
Anyway the slider is here but it's mostly only going to influence the type of instance you are in, and that'll still be heavily dependent on where you are. In safe space, yeah it'll likely keep you entirely safe from players but you'll still face npcs. In less safe areas, not so much and in lawless space it'll likely have no impact at all.
For those of us who aren't too fussed about the slider I doubt it'll really impact us, most of the valuable stuff to find and trade in won't be in safe space after all. If carebears want the goods, they'll have to come out and play.