One person is more important that thousands or millions or billions. That's what gets my attention. It's got to be personal before I give a damn.
That's why I think it's odd. Why should I care about all the deaths on Vulcan or San Francisco when the characters don't? Just like Alderaan was simply to show what a threat the Death Star is and what a bunch of bad asses the Empire are.
If it worked for you, that's fine. I just found it rather callous that one person (or two counting Amanda) gets a much, much greater sense of outrage that billions. What would Spock do if Kirk and/or Amanda hadn't been among the dead? Would he be so much more willing to let Nero live or to not try to beat Khan to death?
It's different levels of outrage - the death of someone close to you will affect you more than the deaths of billions of people you don't know, precisely because it is personal.