Again, the cameos aren't the issue but the idea that it HAD to be there is kind of silly to me. I think most people didn't even connect him to Leia and it's not like there needed to be a huge explanation as to why she was there. A key member of the Rebellion shows up at a battle to get a key piece of evidence that could change the course of the war. Adding, "Because her dad sent her." isn't necessary.