I think the ending works better from a meta perspective from what it says about the entertainment industry. There is a lot of symmetry between Ai in the beginning of the series and Ruby at the end. I think that you can read into it that despite all the tragedies that the Hoshinos have gone through, nothing about the industry has changed and it is more than willing to chew up and spit out young talent in order to exploit it for money. As for Aqua’s death, I was frankly expecting Ruby to die as well Romeo/Juliet style. The ending certainly feels rushed and I wish we had more time with the rest of the cast of characters after Aqua’s death. However, Aka already has his new project announced and underway, so I am not sure how much more passion might have been left on his part to expand the ending.