It's not a minority use case. It's just a use case that is poorly accommodated by a large majority of smartphones. This leads to much higher data usage and higher revenue for carriers than would be the case if smartphones were a little more on the user's side.
I have a smartphone that offers reasonable controls on cellular data use on a per-app basis, in addition to easy system-wide toggles for WiFi and cellular data. It's easy for me to keep cellular data off most of the time, as I'm usually within WiFi range or taking short trips (eg. grocery shopping) where there's no inconvenience to being offline for a while. As a result, I get great battery life out of my phone and don't need a multi-GB data plan unless I'm traveling for most of the month. The TCO for my smartphone is a small fraction of what's typical with an iPhone on a major carrier, but I have full access to the capabilities of my smartphone and its LTE connection, when I decide to use them.
I have a smartphone that offers reasonable controls on cellular data use on a per-app basis, in addition to easy system-wide toggles for WiFi and cellular data. It's easy for me to keep cellular data off most of the time, as I'm usually within WiFi range or taking short trips (eg. grocery shopping) where there's no inconvenience to being offline for a while. As a result, I get great battery life out of my phone and don't need a multi-GB data plan unless I'm traveling for most of the month. The TCO for my smartphone is a small fraction of what's typical with an iPhone on a major carrier, but I have full access to the capabilities of my smartphone and its LTE connection, when I decide to use them.