I cared about Alderaan because it was a planet full of sentient beings; not because of Leia. Hell, on a first viewing you don’t even get enough of Leia to form an opinion about her as a character but I digress. Had Hosnian Prime been Coruscant that would have made the scene more impactful.
It was so poorly explained that a lot of people thought that, haha. I had a moment where I thought the same on my first viewing before they mentioned Hosnian Prime at some point after.