Why didn't the bombers use hyperspace to get closer to the Dreadnought before starting their attack run? The slow approach caused the majority of the fleet to be destroyed.
As we saw later in the film, when Rey is ejected in an escape pod, ships are perfectly capable of dropping out of hyperspace, delivering a payload, and then immediately entering hyperspace again.
In The Force Awakens, Han Solo didn't seem to have any problem dropping the Millenium Falcon out of hyperspace remarkably close to Starkiller Base to avoid detection. It appears that such a maneuver is not only possible but could be used frequently.