It is interesting to compare how Luke and Anakin were exposed to loss . Luke didn't have premonitions about Owen and Beru's death, just suddenly they were gone. He never had that period of "crap, this might happen, how can I stop it?" followed by the "crap, I was too late to stop it, but if I were only a little quicker!" He didn't have to doubt his actions like Anakin did with regards to his initial losses. The second he has a premonition about Han, Leia and friends, he immediately starts freaking out and becoming pro-active against it. That's why Yoda and Obi-Wan are worried. Suddenly it's Anakin's need to help his friends as a priority over the greater good of the galaxy shining though. It's a very volatile situation.