I think some of you are missing the point of the randomization. If you analyze anyone’s playing, from beginner to virtuoso, you will find all of these parameters we are talking about (velocity, position, length etc.) have a level of randomness involved. It is a window around the “target” of a performance. The difference between a beginner and a virtuoso is that this window gets much smaller as mastery is achieved, but this window of uncertainty is always there. You cannot play a beat exactly on time or a violin exactly in tune. That’s not how physics works. You can only get close.
The difference between this randomness and a “groove” is that applying a swing is still a mechanically quantized pattern. Applying a groove to one bar and copy/pasta that for the rest of your piece means you are repeating it exactly the same way every time. Humans don’t do that. Well trained musicians can relax the beat, swing light or heavy, play “off the grid” etc, but there are still slight variations in actual performance as compared to its ideal. Think Platonic solids. There is no perfect “sphere”.
By all means, use the grooves to get the feel you are looking for, but don’t confuse it with the randomization element. They are both useful.