…I’m not sure how much sense that makes either: let’s fly out on barely functional crafts with limited maneuverability to a bunch of AT-ATs and a big gun and hope it doesn’t fire until we are really close so we can shoot at it.
To quote Antiope in Wonder Woman “You expect the battle to be fair! A battle will never be fair!”
The rebels were using the ships they had left. It was either that or sit in the entrance to the cave, put a marshmallow on a stick, and yell incoming!
If they could have gone out on a Star Destroyer and blown a FO-sized hole in the ground, I suspect they would have.