"I know that some people need to carry an EDC pistol which carries 15 or more round".
May I ask Why? What are they doing, and where are they going that requires a 15 round mag if they are not in law enforcement.
I guess there are some who think the gunfight at the OK corral will happen most any day....and they need to carry an AR-15.
I can see the need for 15 rounds, if you ever encounter a mob/demonstration situation, you might have to fight your way out of.
It's becoming common in Detroit, in recent years, when you're involved in a traffic accident, a large group of angry, aggressive neighbors, family, and bystanders, begin to gang up, and seek to get revenge, and carry out their own type of street justice, right then, and there!
Then there are the pro/anti-gun demonstrations, political demonstrations, that you can find yourself unexpectedly involved, at some level. Mall, church, event mass shootings, etc.
That being said, I typically carry a 5-shot J-frame, with two loads of additional ammo. If I know in advance, I'm going to be passing through a high-threat area, in addition to the 640, I bring a 686 Plus, for the truck gun. Both guns share the same ammo. I have to go into Flint, MI on occasions, and they have gangs, and they don't have a very responsive police department. So if you encounter trouble, you're likely on your own. The PD shows up later to do the paper work, and haul away the body.
So back on the OP's topic, if you carry a single stack semi-auto, just carry a couple extra mags. This balances the weight better on your belt, than a really heavy pistol on one side, with nothing on the other side.