Really? Would there be a strong negative reaction if Apple said "we've designed the iPhone 9 to give you all-day battery life for four years"? Would customers be angry that their device was built to last longer and perform better? To my mind, it's a marketable feature.
All battery management is a trade-off between capacity and durability. Manufacturers have an obvious commercial incentive to sacrifice durability - you get a thinner device with longer initial battery life.
Purchasing habits are starting to change in the mobile market. Pricing is moving away from an all-inclusive line rental price to separate usage charges and device payments. As the market matures, customers are holding onto their devices for longer. I think it's inevitable that manufacturers will have to improve durability as we move away from the lock-step of 24 month contracts.
Consumers are responsible at least as much as manufacturers for the current state of phones. Manufacturers may create the designs for phones, but consumers vote with their wallets for what they want, and they've consistently voted for thin over longer battery life.
Most consumers don't understand battery technology and don't know what's available on the market. They go into their local cellphone store and choose whatever looks nice and is recommended by the salesman. They aren't aware of handsets with bigger or user-replaceable batteries, because the industry hasn't really offered them the choice. I use a Chinaphone with a giant battery, but I have a lot of knowledge that no average consumer has.
You’d restart the phone and after a second trip to the battery indicator would show the correct level (let’s say 60 to 80 percent).