In some aspects, smartphones have become toys. Scrolling through reddit/facebook/twitter doesn't really make it worth having a smartphone, since those are all dumb activities.

However there are certain features that a smartphone gives which I wouldn't give up. Navigation with google maps, being able to do banking services on the go with my bank's app, being able to review flashcards with the Anki app, having my railcard/tesco clubcard/nectar card on my phone and never losing it, being able to check any important emails, checking the news if something breaking happens and I need to know instantly.

Heck, we praise Apple for bringing services like calling an ambulance for you if your pulse shows a certain pattern matching a heart attack (via the apple watch), and we also praise smartphones for actions like alerting people for emergencies like a terrorist attack or issuing weather warnings. I wouldn't give up any of those features just to have a dumb nokia phone with a week-long battery life.

Highly recommend you check out this: https://www.blloc.com/

Why give them up? Have 75% of the battery life be used for all of those activities, but build the phone so you could still make calls and send text messages for a longer while later.

Also - Smartwatches are silly IMHO; and people can be alerted just fine with a voice or text message.