I'm not sure I'd put sunscreen and chapstick in the "convenience items" category either. Sunburn, in particular, can be life-threatening. Sunscreen won't prevent you getting sunburned, but it will reduce the risk. And having cracked and swollen lips after a couple of days might be more than an "inconvenience".

Did you forget to mention triangular bandages and sterile dressings? Pretty much every first aid kit I've ever seen has at least a couple of each.