Because it's not insanely fast? The 256GB is pretty slow (why is that even an option though?) the higher capacity ones have are considerably worse compared high

Because it's not insanely fast? The 256GB is pretty slow (why is that even an option though?) the higher capacity ones have are considerably worse compared higher-end WD or Samsung2 SSDs and you can get a 1-3TB one for around $100-$300...