Sometimes, when you develop something and the resulting software always works like a charm, you can get a very unpleasant surprise when you run some final tests on a different setup...
The tarballs were primarily designed to fit the script sets' upgrade functionality (the 'get' function). At a certain point I figured adding a simple install function would be useful. So I built and tested it, using my standard tools on my Xfce system.
Now one of the first things I did when I switched to Xfce, was get rid of Thunar. As a file manager, it's an absolute joke. At least it was then and recent experiences indicate it hasn't really improved where it counts (there's actually an 'Extract here' entry in the context menu now - yay! - only it doesn't work right...).
So I use caja these days, after nautilus went down the drain and nemo started filling up my system's .xsession-errors file (thank you, GTK+ developers, you obviously hate your users just as much as the GNOME developers do [edit: just realised they're largely the same people, so no surprise there...]). When you ask caja (and nautilus or nemo) to 'Extract here' an archive, it puts the contents in a separate directory, whether the archive actually contains that directory at its top level or not. Dolphin can do that too, if you select the entry which mentions auto-detecting the subdirectory.
Thunar cannot do that automatically, so if you're not careful and forget to create the subdirectory yourself, everything ends up a level too high and possibly spread all over a directory filled with other files. Good luck cleaning up that mess.
I could modify the tarballs, but that would break the upgrade mechanism of the script sets which are currently in use and outside of my control. An alternative fix would cause caja et al to create an extra top level on top of the one added to the tarball, which would make using the script in situ a pain and complicate the install function (and make it fail on Thunar - again). So I'm not going to change the tarballs.
Sorry about that.