My previous handset was the Droid Turbo, which had a large battery. I could easily get through 36 hours with it (48+ with light/light-moderate use). While the V30 has good battery life, 30 hours is about the max I've been able to get out of it, and that is with light usage on a good WiFi connection all day.
I'd love to see larger batteries become the standard, and it can be done without adding much bulk. However, as girl_interupted touched upon, OEMs won't do it because it may translate to a dip in sales. Most average consumers will get a new phone either because their OS gets bogged down or the battery life degrades to a frustrating level. A larger battery would obviously last longer and allow for a wider margin of entropy. Thus the consumer won't feel the need to upgrade as quickly as they once would.
OEMs know that as long as they provide a system that can get through 16 hours of use, consumers won't demand a larger battery because most don't consider lifespan.
It's not a fluke that OEMs are ditching removable batteries. There's a business reason for the move.