Unless I don't understand something, this actually won't help. The purpose of defragging on mechanical drives, gets the data closer together so that the head doesn't need to go seeking all over the platter for the data. Also I believe it moves the data toward the outer edge of the platter since speeds are faster out there. This can end up gaining space, and also increase the speed of things. All of this makes sense for a mechanical drive.
Flash memory doesn't have seek time, or very low at least. As there are no moving parts, so grouping the data is rather pointless.
I of course can be wrong.