Instead of restarting my lisp. (without force, an already loaded package won't be recompiled and reloaded, it will just be left alone)
To some extent it is also an encouragement to use the feature rich uiop:define-package and corrollary support for understanding dependencies between files/packages in a given asdf system, though uiop:define-package can be subbed for 'defpackage without using :package-inferred-system .
You can use :force t without package inferred systems. If you want to force just a single file, you can just load it. I find that package inferred systems is a nasty tight coupling of packages, systems, and directory structure (files). These 3 things are all perfectly happy being loosely coupled.