IK doesn't "solve" the core problem of realistic character motion. Sure you can tweak foot positions to stop them from sliding but the farther they get from the original animation data the worse the result will look. It's no panacea.
There are new approaches to generating realistic character motion being shown at SIGGRAPH every year, getting better and better, but the best ones are largely too expensive for games to adopt. Plus, for player-controlled characters, at a certain point you run into a fundamental tension between control responsiveness and physical realism of animations.
IMHO IK provides enough to counter the issues the person I was replying to was mentioning.
Now of course you can go above and beyond that for more realistic motion and , but having worked in the space, I would Serguei that is also solved without requiring recent research. Most recent motion research is about novel motion generation but the general problem of dynamic adjustment to authored animation has been solved by several systems already. But just like my original comment, there’s both a development and runtime cost to all of this.
There are new approaches to generating realistic character motion being shown at SIGGRAPH every year, getting better and better, but the best ones are largely too expensive for games to adopt. Plus, for player-controlled characters, at a certain point you run into a fundamental tension between control responsiveness and physical realism of animations.
I recently saw a great article on the topic which even comes with a WebGL demo: https://theorangeduck.com/page/code-vs-data-driven-displacem...