This is a pretty general question.
Why do starships need to take off and fly straight past the incoming ships in order to be able to get away? (I know, film reason = because it's cool)
Eg The rebel transports in Ep V need the ion cannon to "clear a path". Why? Why couldn't they take off, fly around the planet, then break for space in a clear spot. Same for the Naboo cruiser in Ep 1, and blockades in several episodes of the Clone Wars. The planetary blockades only seem to be on one side of the world.
The hyperspace point they want might be along that line, but if they're being chased surely they could just jump to anywhere, then recalculate for their original vector.
I can just see players arguing about this in my near future...