My take is that while Han, Luke, and Leia are key figures in the Rebellion, using the entire Rebel force to rescue one guy seems like a very stupid move when they've been planning the attack on the DS2 for Lord knows how long.
So what seems like the greater risk? Sending a few capable fighters to save one of their Generals? Or risk missing the window on being able to possibly overthrow the Empire and by extension, liberate the galaxy? Save a single life? Or potentially save the lives of billions?