I use iTunes Match so music storage is never a problem. There are tons of cloud services for pics & video. I get 500GB storage with my Godaddy biz account for example.
On my 32GB iPhone I have never used more than 8 GB on apps.
Some people feel more secure carrying their physical media with them. While I don't understand the resistance to adapt. I respect their choice and think the option of more storage is justified. Just like the people who still write checks at the grocery store but have a debit card in their wallet. Both are immediate withdrawals, but for some reason they feel more secure handing somebody a piece of paper. /shrug