Full-body IK Solvers (IKinema) purpose (ELI5 )

Hello. Could somebody explain why people use full-body IK Solvers like IKinema? I have researched the topic, however, I still struggle to connect the dots, because most of the information I could find was targeted at people who already know the use-cases for such plug-ins.

There are several reasons why this type of software is handy. I have used it with vr games so that the player can have a full virtual body to enhance game-play. I’m not very familiar with IKinema specifically but other solutions (possibly IKinema) also support motion recording allowing developers to create more realistic animations for character models. Basically given minimal data points ( say hand positions using controllers) we can “guess” how attached bones would behave (i.e arms) and use this to drive skeletal mesh animations