It seems counterintuitive, but a round nose causes a lot more drag than a flat nose, the flat nose causes a small cavitation bubble around itself so that only the flat surface is in contact with target, while the round nose is contacting the target on the majority of the ogive, making it dump energy faster. Flat nose bullets are best for when you need extreme penetration on very large targets, for instance in an elephant gun shooting brass solids at rhino, hippo or elephants. If you look at a lot of elephant gun cartridges you will notice most of them are shooting flat nose, with some using round nose for slightly smaller, more dangerous game.
Flat nose rounds don't tumble very easily and penetrate deeper. They don't usually do as much damage as they would if they were to tumble, but it's a different tool for a different job. If I was relegated to using fmj for self defense I would use round nose. If I was gonna carry out in the woods for defense against animals, then I'm probably taking a flat point
