It isn't really confusing because when I go check how much free space I have on my hard-drive I'm just looking for a rough value, it can be base-10, base-2 or just "lots", "enough" or "almost out". The same happens to files and directories, I just want to know if they are "huge", "big" or "reasonable".
The problem is that the "old way" of reporting units in base-2 served the same purpose in exactly the same way. But this gratuitous change brings an heterogenous environment that causes problems when I want do do scripts or somesuch technical stuff where the exact amounts _do_ matter, and now have to worry in which base they are (and often this isn't obvious).
Consistency was dropped for nothing.
As for Ubuntu, I think this is a "me too" move that serves no purpose. But hey, I don't use Ubuntu, so I couldn't care less.