Bear with me a bit while I push back on that a little. Perhaps I have a different expectation of what the drag event is supposed to be.
I do see that the description in the documentation is 'This event is triggered when the mouse is moved during the dragging.' I guess my expectation is that the event should be triggered when the item is moved, not when the mouse is moved, since there are other ways to track mouse move events. I am not sure why I would want to see drag events constantly if no drag happened. By setting a grid, I purposely am saying, 'Don't move until you go a certain distance.' Why would I want to know that the user tried to move it, but it didn't move yet because the user hadn't dragged far enough?
Re: ui.position, if I set an axis, why would I want to know in the drag event what would have happened if I didn't specify an axis setting? It is strange to me that ui.position.left is changing if I set axis to 'y'. In addition, if I have an axis setting of 'y', and have a grid setting of '5', and I drag to the right, I see multiples of 5 in ui.position.left, even though it doesn't move in that direction. I would think the developer would want to know the actual position of the draggable, not a hypothetical position if the axis value had not been set.
Finally, is ui.originalPosition supposed to be valid, and what should it be set to? In particular, I am noticing that the first time you drag, it is set correctly for drag event and stop event. But if you click on the same item and drag it again, it gets set to what appears to be a random value. I would think it should be set to the top-left of the draggable object at the moment the item is clicked the 2nd time.
If its still decided to keep the drag event as is, then I would request a 'move' event, that would fire each time the draggable moved, and only when the draggable actually moved, and would update ui.position with the new, actual, top-left location of the draggable, and would update ui.originalPosition to the top-left of the draggable each time the object was clicked.