While I appreciate that there is a kind of crime story where the solution is not important, I think that getting to the truth is at the heart of Veronica's life. Granted, if she had found out only the story behind the GHB nightmare (minus the Cassidy retcon), I think that might have been enough to satisfy her. She might have been able to move on without solving the Lilly Kane murder. Then again, the entire set up of the show was built on that.