Peter has to calculate everything related to the physics of a pendulum for every single web he shoots, using all sorts of formulas, equations and other mathematical concepts. With time, he has learned to do all of those automatically and instinctively.
This means that everything he does while he's traversing through the city is based on
REAL PHYSICS.
This emphasizes how much the very concept of the Web-Swing is DIRECTLY connected to Physics, at least in the more modern versions of the character, and how Peter's cognitive skills are responsible for his acrobatics and amazing movements. His Spider-Sense allows him to feel everything around him, while his big brains allows him to know exactly how to use his surroudings to accomplish what he does.
Well, I'm not making equations in my head, but I have a pretty decent idea of how a pendulum turns in the direction of it's traction point. With that, this realistic style was born.
Why does this matter?
Well, it matters a lot if you're the pendulum.
