I don't normally care about the difference between floating hands vs a body. When it's done right, like Echo Arena/Lone Echo, its great. If the hands are all alone, I don't care. Sometimes you don't even get hands, just a default wand model or a weapon.
The problems crop up not when you have a body and its bending awkwardly (and is otherwise just an elaborate skin for floating hands), but when you have a wobbly IK body that affects the gameplay. A game that does this haphazardly is Sword of Gargantua. In the original demo, the body's geometry got in the way of your vision when looking down, this was changed later. In both the demo and the final game, your character's swing speed, weapon swing angle, weapon positioning, overall hand placement, and damage output is tied to your in-game floppy IK arms instead of your actual controller location in real life. The arms also have a processing delay, so they are always lagging behind your movements. It makes the game much harder to play than it should be, but that's definitely not the only problem I have with that game.
Blade & Sorcery and Boneworks are two other prominent games that could be affected in the same way, but I have yet to play either.
