Longer battery life is always good. However, we don't always needed bigger batteries. There are loads of ways to reduce battery drain in the HMD phones using the Android settings, most of them relating to background processes and disabling apps which aren't being used. My Nokia 8 should apparently need a charge once per day, but I can easily get two days of use out of it (note that I have the screen brightness lower than most people).
Anyway, in general, I hope that battery life improves in the next generation - I remember when my N8 running Symbian only needed a charge two or three times a week!