I also like that idea. Except that that's technically far more difficult than one would think at first.
For one, no interpolation doesn't really make sense, I suppose you meant linear interpolation.
Then the next problem is that linear interpolation is between two keyframes (not on one keyframe).
To make matters worse cubic interpolation is between three keyframes.
So not only would that be a nightmare to store and create GUIs for but more importantly to interpolate between who knows how many different keyframes.