We have no plans to introduce such a feature at the present time. It’s (in my opinion) really bad practice and makes the music less legible rather than more legible. I imagine this practice arose from hand copyists ruling all the barlines for the page up front because they had their straight edge in hand and wanted to work as quickly as possible, rather than because they believed that having every bar precisely the same width is actually desirable.
Having barlines aligned at the same horizontal position across the page makes it a bit easier for the player to get disorientated as they read each system, so having the systems looking a little bit different in terms of their spacing and density helps the eye to follow the flow of the music. Not to mention that, fundamentally, you don’t want the note spacing ratios changing on a bar-by-bar basis, which is what would be needed to make bars with different rhythmic contents the same width. Such music would look very uneven and without decent proportionality in spacing, the music will appear “lumpy” to the person reading it.
I know that there is music out there in the world that is laid out this way, and you can achieve it in Dorico with a bit of manual work, but (in my opinion) it would not be a profitable use of our limited development time to try to make Dorico’s layout and rhythmic spacing “worse” for these kinds of layouts.
Sorry for the disappointment!