Why do I carry a big folder? The same reason you wear the shoe size you do.
They fit me better.
Just because I carry a bigger knife, doesn't mean I'm constantly running into things a Delica couldn't cut. I went a month EDCing my Street Beat, and like you there was never a situation where I couldn't cut what needed cut.
The bigger knives simply do the jobs more efficiently and safely.
Think about your kitchen. Family comes over and you're cooking dinner for 8. Could you prep everything with a paring knife? Sure. But why would you when you've got 8" and 10" chef knives that can do the work 3x as fast?
Millie can cut an apple in half in one cut. Delicas take 2.
When breaking down boxes large blades are at least twice as efficient. I can stack layer upon layer and slice through the whole stack instead of doing it piece by piece.
A folder with a 4" blade is just as precise for tip work as smaller knives for me by using this grip.
The smaller knives don't offer me any benefits, just draw backs. Less efficient in use, less comfortable to hold, often times not built as rugged etc. Big knives tend to have stout locks, thicker hardware etc. that give me more confidence in use.
Taking a Delica for example, the handle feels bad to my grip. The handle isn't even as long as the width of my palm, and there's no good place for my thumb:
VS the Police:
Often times on old hiking & cycling trails there will be briars growing across. Using a Military or Police gripped behind the main grip like in the following picture, I can use them like a pocket machete to make the trail safer.
I can't safely hack down briars with a Dragonfly.
Yesterday I use a Pacific Salt to slice up a memory foam mattress.
Delica would have been too short to slice through it in one cut as easily. In fact I had grabbed a longer knife because I wasn't sure if the Pacific would be long enough, but it ended up getting it done.
So it isn't so much that I'm constantly slicing up watermelons on the go or something. But rather more blade means fewer cuts to get a given job done.
Try considering it from my perspective:
1. There are no legal restrictions on knives where I live & work
2. There are no social taboos against 4-5" bladed pocket knives where I live
3. Even in my light summer shorts, I find 5oz and 5.5" closed to be my rough limits on comfortable carry. This includes the Military, Chief and Police LW. My Military is IWB in my running shorts right now, perfectly comfortable
4. As outlined above I find them more efficient in use, and even safer in certain situations.
5. I wear a size XL-XXL glove, so picking a folder that matches my hand size is simply logical.