You are at least the 100th user to request this. It is natural think of score writing software as analogous to staff paper and pencil (and eraser), but Dorico’s design philosophy is different: Notations are put on the score to have musical meaning, and not merely graphic appearance. And programming these features to work musically takes a lot of thought and time. The result is that the task of writing standard notation has been streamlined way beyond previous software. But more recent and less common notations (such as aleatoric boxes, also often requested) have to wait until they have time to work out a comprehensive and semantic approach to each one.
For contrast – Finale treats the document more like staff paper onto which you can write anything you want, whether it has musical meaning or not. This has so far been more useful than Dorico for modern composers who need to write lots of nonstandard or less common things on the page. But I think that is a niche of a niche market. Dorico is trying to serve the needs of as wide a user base as possible, and they are adding more kinds of notation as soon as they can.
(If you do need aleatoric boxes, I recommend the font in this thread, or for a more comprehensive survey of workarounds, see this video.)