What if Jabba had accepted trading C3PO and R2D2 for Han Solo? Or if Leia had managed to escape with Solo without Jabba noticing, leaving the droids behind? Wouldn't that be a horrible thing to do, leaving the droids with Jabba just to get Solo back? Then, he would probably have to fight to get the droids back anyway... So, either way, he would have to resort to violence. Well, either Luke didn't have much of a plan and decided to just throw in everyone at the same time and see what happened, or he thought he would resort to brutality anyway, and thought this was the best way to do... Quite Sithiistic, if you ask me.