Define a tech nerd then.
Tell me things a tech nerd would do differently on their phone compared to a casual user that would require so much more storage space. Do not include apps, photos or music though because casual users would definitely install large apps (FIFA 15 for example which is over a Gb), photos because many casual users take hundreds of photos. Music partly because Apple are marketing Apple Music (each song has a higher bitrate). When I first bought an iPhone I wouldn't have considered myself a tech nerd however I had a large iTunes library which I synced to my phone.
The people I believe you are referring to in terms of these casual or general public populations are literally children or mums.
People aren't as tech illiterate these days.
Okay. I could get by with a 16GB phone. Here is what I use my phone for and I think I'm pretty similiar to many mainstream people:
Calls
Text
Stream music
Stream netflix
Stream TV shows
Podcasts
Web
couple dozen apps
Couple hundred photos
That's pretty much it. I don't have massive resources on my phone. I see no need to keep music/movies or an abundance of photos on my phone.