It should automatically add z-index in version 2. Why do you need to update it? What do you update and what do you update it to? Since we figure menus will probably always be on top, I'm not sure we would expose it, but we could automatically set z-indexes to something that should work for people. Which is what I believe we have done unless we didn't do it everywhere we needed to for some scenarios.
Please let me know exactly what you are updating and why and I can try to get it in as a feature request to handle your use case.