Presumably for the same reason the original death star couldn't hyperspace around Yavin in A New Hope.
I blame the midichlorians
( ,
Wed 17 Jan 2018, 9:47,
archived)
I don't think the death star could do hyperspace at all
But all the new order lot definitely could
( ,
Wed 17 Jan 2018, 9:51,
archived)
I think it would have to
otherwise it would take hundreds of thousands of years to get anywhere
( ,
Wed 17 Jan 2018, 10:15,
archived)