It has indeed been requested many times before, and it’s something we do plan to add in a future version, though it’s a bit more complicated than it may appear, due to the fact that in particularly dense chords Dorico can end up consolidating multiple rhythm dots belonging to different noteheads, and under those circumstances it’s non-trivial to determine how to position the rhythm dot if it has inconsistent property values. But, as I say, it’s definitely something we plan to tackle at some point.