Don't take this personal, it's not aimed at you.
I'm just gonna say why would they make the spring if it want meant to be used
Because there's a market. That market is, at least for a good part, people who get their juices flowing with the thought of the highest possible FPS. That market is idiots who up their rifle to well over field limits and disregard the safety of others. Usually the type of people who will show up at a FPS test with .40g bbs in their mag and telling the marshal it's .20g or .25g, hoping to go by undetected. These are the same type of people that buy a HPA kit and once they've passed the chrono open the regulator to get even higher FPS.
Now, there are people who use those stronger springs in setups where they will remain under the field limits. In some cases field limits border on dangerous, in other cases their rifle is equipped with the aforementioned wide-bore barrels, meaning they can use a stronger spring at the same FPS. Others take a slightly stronger spring and cut it so it creates less (or no) noise.
To install springs that strong, you will need to upgrade a trigger mechanism or the gun won't last very long. Depending on the quality of the cylinder, that might also not last too long. I don't know the quality of the SW M24, so I cannot be sure.