Delete App Installation Files
I find WP8 won't delete app installation files, even if you unstall them. Those installation files occupy "other" space. The problem becomes poorer as user installs more apps. A big problem is WP8 uses only "free" space to decide whether or not user can install new app and add video, music, ... even if "other" space has many space to be released.
Please provide a function for WP8 to delete the app installation files!
You can try to install a large-size (e.g. 500 MB) app and then uninstall it. Then, please calculate the other space difference between pre-installation and post-uninstallation.
As far as I know that is not what inflates the "other" storage, that is rather temporary files like Images downloaded in the Images Hub, etc.
It's a serious problem...
A smarter solution could be: if user installed an app with size more than free space, WP8 would automatically clear the temporary app installation files. If the free space is still not enough, WP8 just notifies user.