Naw, just usefulness. The hell am I going to put in a little satchel? I either need my pockets, or a backpack. Never needed anything in between.
There's a lot of stuff that you don't need a whole backpack for that is too big for your pockets these days - primarily due to the rise of tech.
Especially for urban area living where you are taking mass transit a lot, or bikes. If i'm driving around I rarely take a bag with me. But if I'm on two wheels or in the subway and cabs/ubers, I'll throw in my small sling my kindle to read at the park or on the train, my Senn true wireless earbuds in their charging case for some music options. With phones being so essential I just keep a small battery pack and charging cable in there just in case I forgot to charge my phone or am spending the whole day out and about. Plus it's a nice place to throw your keys in when walking around instead of hanging off your belt on a carabiner and jangling about.
Nowadays I'll throw in some hand sanitizer, eyedrops for my contacts, maybe a case for my aviators. That's pretty much it. If I'm riding in the heat, a microfiber sweat rag, cause I get hot easy and a couple energy gels. Also for biking, a sling is often better than a backpack, you can slide it right in front of you and utilize it while still on the bike easier than a backpack. Slings are also much faster for photographers to do lens changes and the such since you don't have to take them off the body to use. If it's a bike ride and I don't need much I'll take a smaller sling - throw a patch kit in there, my bike lights and u lock and go. It's just that much less surface area pressing on your back to sweat from.
There's a whole lot of reasons for different styles/sizes of bags. Of course now during Covid I don't do much out of the house for fun besides hike, then I just take a backpack with me.