Sometimes you forget to charge your phone. No problem! Battery's good until you get to a charger sometime the following day.
Also, an oversized battery / efficient chip means I can power-use my phone for a full day without worrying about battery.
And finally, because as your battery loses capacity over time, your phone drifts back to one-day charge, not sub-day charge.
I, too, loved my Droid Turbo. When I first got it, I remember driving from San Diego to the north edge of the Los Angeles metro area over about four hours using Waze. 4 hours of screen and GPS time and it only used about 40% of the battery. But after 3 years, 1 hour of Waze would consume 25% of the battery. The battery would barely last me a day, and if I was somewhere where I wanted to take a decent number of pictures, it wouldn't last more than a couple hours. I bought a replacement battery, but even though the battery was new, it was built years ago and was still slightly degraded.
I ended up buying a Pixel 3. The battery is only 3,000 mAh IIRC, but it's quite efficient. I usually finish my day with about 30-50% of the battery left depending on my usage. Of course, it'll be a different story in 2-3 years.
I went for the Pixel 2XL, for the battery and for the software updates. Can plug in my phone for an hour here and there at random times, and no longer leave it plugged in at night. I can go out or visit family with battery at 50% and not worry about my phone dying.
Google's fast charging also seems to be more variable and "smart" than motorola's, and doesn't seem to overheat my phone as much