While I dont remember ever having stacks of units of Soase:R, perhaps it is because I havent played it since, however the current panel does not fulfill the information display that would show all useful info, not having to pin planets and units to the left side, same for fleets, but having it organized in what I remember as not missing details, soase 2 interface looks more of a filler that would remind of the old game, while not providing the functionality of the old game. Meaning, all the displayed things give me indications instead of actual info. You could minimize it in the old game thats what I remember. That it doesnt provide precise info acts as it is not being worth filling up the space.
So, for me personally, if there was possibility of simply porting old UI however outdated it looks, I guess you could pretty it up, I do think it was a reliable conveyor of useful information, much more so than the new one.
Also when selecting fleets and having to deselect it twice to get out of fleet build and only then getting to the actual fleet is what also didnt happen with the old system. It felt user friendly, it was much harder to lose sight of units there etc.