For many, a recoil spring is the primary component in mitigating the felt recoil and muzzle flip. This is true for the most part today. But I think alot of people forget the other functions of the recoil spring and how important it is to have a well engineered spring system, not only for lower recoil, but generally reliable functioning.
The basic principle to understand is the fact that all semi-automatic firearms rely on one thing in order to ensure reliable and safe cycling. And that is making sure that the system has sufficient dwell time between the time when the primer is struck, and when the round is extracted. This process is a very big deal for semi-auto pistols in particular. This is done in two ways, having a certain distance to the point of unlock before extraction of the cartridge begins, and having a spring system with the right amount of tension to delay and control the slides rate of rearward movement.
With pistols, you may find that there is a sweet spot where you are delaying the unlock, whether with springs or distance, just long enough for the pressure in the barrel to drop to safe levels, but still have enough momentum and inertia to be able to eject the rounds reliably. This becomes increasingly difficult when you add in the fact that pistols these days are expected to be able to reliably cycle any round on the market, or else suffer from being declared a useless piece of junk. But manufacturers have come up with several different recoil spring designs that work well for the most part. They all do the job a little differently, and use different materials and construction. This is just the way it is nowadays. Personally, I find it interesting how well thought out some of these designs are. But there is evidence of there being plenty of room for improvement in the realm of pistol technology.