Not only does baking reduce the need for recalculations, it also ensures that dynamic effects are rendered exactly the same across different systems. This becomes especially important when you're network rendering across multiple computers. Different computers can have different levels of calculation acuracy, meaning a dynamic effect, such as the random generation of particles from a particle emitter, may not generate the particles in the same place on different computers. Imagine having two computers rendering a complex particle stream, only to find out that the particle positions in the frames rendered by the second computer don't line up with those of the first computer. Baking solves this problem by converting the dynamically generated numbers into real translation, rotation, scale, etc. data on the timeline.

Another time baking comes in handy is when you need to keep particles and other dynamic effects acting exactly the same each time an animation cycles is played. For example, if you made a dynamic bowling ball hitting bowling pins and you wanted the pins to always move the exact same way, you could bake them.

I hope that helps.