Yeah, it should be off by default, but don't even think of getting rid of it. I've found it very useful for starting certain types of poses. Put a figure's hands on a wall, for example, turn IK on for the arms so the hands stay stuck, then do your fiddling with the body. Or stand a figure in front of chair, turn IK on for the legs. Grab the hip and pull down. Turn it off again for refining. I think if it were off by default, and easier to click off and on, folks wouldn't gripe so much, turn it off, then forget it exists.