Simple precautions. As you pointed out with Firefox, some times unintended dependencies find their way into a package. Uninstalling a large block of packages can cascade into removing a lot more than you intended.
True, if you know *all* the packages that are involved, a careful review of the delete list would reveal this kind of error. Such intimate familiarity with your system is normally reserved for advanced users. No one here would consider anyone "stupid" for not possessing that knowledge.
Gslapt is a GUI front end for slapt-get. The safest method is "removepkg", which has no dependency checking.
As pointed out by others, the path of least resistance is to just add the WM or DE of your choice, and make it your default. That way all the features of SOHO will be at your disposal, but not running unless you call for them.