SilverWook said:
Of course, none of this explains away making an even bigger design flaw than the original. Exhaust ports big enough to fly into! ;)

They didn’t see that as a design flaw because those exhaust ports were protected by a shield they believed to be invulnerable.

As long as we’re on the “Why didn’t they...” theme, I don’t see why the Rebels decided to let everything depend on a ground assault force defeating the (assumed, for no good reason, to be small) Imperial force protecting the shield generator and placing explosives. The Alliance may not have had the power to destroy a planet, but they certainly had enough firepower to blast a sizable crater in one. Why not take out the shield generator by nuking the entire site from orbit? (In the words of Ellen Ripley, “It’s the only way to be sure.”) Is there any reason given why this wouldn’t work?