The appeal of a "Portable Crack" is rooted in the desire for a clean, non-committal relationship with software. A portable app doesn't require installation; it leaves no traces in the registry and can be carried on a thumb drive. It promises the utility of a powerful uninstaller without the irony of having to install yet another program to manage your programs.
Complete removal of registry entries, cleaning up leftover "junk" files, and forcing the uninstall of corrupted software.