The reasons currently given for why someone should care to learn these new things are not particularly convincing for busy people building apps for connected, first-world audiences.
Your app won't work on Mars
Your app doesn't work on the WiFi-free underground trains of the backwards cities of the world (here's looking at you, USA)
Your app won't work for a little while for people on planes who refuse to purchase expensive WiFi
You app won't work for people at conferences with flooded WiFi who don't want to use their phone as a hotspot
Your app doesn't work for certain niche world markets that you're not targeting anyhow
Your app isn't resilient to extreme government censorship & internet shutdown
Compared to the clear market-driven reasons that web developers everywhere adopted Mobile First ("50% of emails are read on a phone" and such), these reasons aren't very motivating.
Ideas of other motivations to give:
Natural disasters can ruin connectivity for whole regions
Offline First is but one positive side-effect of better app architectures (reference) (Not sure this idea fits within this talk, tho)
Our data is not owned or controlled by us (reference)
File size scales faster than network speed, making web feel slower as time goes on
Find other motivations in talks like the Stanford Seminar and Offline First talks.
The reasons currently given for why someone should care to learn these new things are not particularly convincing for busy people building apps for connected, first-world audiences.
Compared to the clear market-driven reasons that web developers everywhere adopted Mobile First ("50% of emails are read on a phone" and such), these reasons aren't very motivating.
Ideas of other motivations to give:
Find other motivations in talks like the Stanford Seminar and Offline First talks.