Besides making your application more comfortable to the user by servicing the text and images in their native language there is an extra benefit of localizing your Windows 8 applications.
The Store application has an option to ‘Make it easier to find apps in my preferred languages’ under Settings -> Preferences. This option hides all application that are not localized to the language that the user selected when installing Windows 8. For a Danish user whom selected Danish as the primary language this means that the Store only display apps that are localized into Danish. This is crucial to note, since your app might not even show up in the Store depending on the user’s preference.