What's the point of any of this dogfighting when you can just build a hyperdrive capable missile and
Look at Empire running around building deathstars, and planet killers and super star destroyers like chumps.
Although as it turns out it's not the ship going into hyperspace that causes the damage, it's the weight of the character being sacrificed that does it. You need to have had a minimum of 5 minutes of screen time in a starwars movie, with dialogue, in order to pull off this maneuver.
Characters with less exposure than that can still crash into enemy ships but they will only be able to destroy small sections of the enemy craft equivalent to the ship they are piloting.
That limits the total number of potential fleet disrupting hyper missiles to the dozens. Once those sacrifices have been made, there will be no one left to carry on the story and the war will end as everyone who is left just walks off, stealing what they can on their way out.
The true power of the empire is the fact that hordes of nameless npcs can destroy the galaxy so long as there is at least one partially crippled angry person sitting in an uncomfortable chair to give the orders.
The rebels on the other hand have to sacrifice minor characters to achieve any meaningful victory. This makes recruitment really hard. So basically what ends up happening is anyone who can't pass the empire employment screening program defaults back to either smuggling, running a cantina, operating a junkyard, opening a merchant stall, farming or as an absolute last resort, joining the rebels.
So it's not that the rebels haven't known about hyperdriving their way to victory, it's more about the fact that they are desperately fighting public perception that The Rebels inc. is where careers in the space fighting industry go to die. Incorporating self destruction as a primary tactic is the last thing HR wants to see.