Most of the tools in the Toolbox pod in Classic haven't been updated in 20 years or so, I think. It's possible some no longer run. Also, there are better third party options are available for a number of them (for example the graphics locator tool and RoboScreenCapture). So probably Adobe decided they were out of date and no longer relevant.
There may be an argument for including the ones that deal with CHM (HTML Help files) though, such as the csh test and help studio.