Difference with plain aliases?

With Drupal menu system, you only can add a real path in one menu (it's a core limitation). When we are developing an i18n website, normally, we have different menus for each language. Making per-language path aliases don't solve this problem because, Drupal menu system saves the real path nor the aliases. This can break the breadcrumb, menu_block, etc.

With this module, you've one real path for each language.

You would even have the capability to set the active menu handler on a custom code basis and thus aliases might work.
(Menu items with language are more specific and thus are subject of higher match priority than language free items.)

Note that we initiated an extension where drupal (i18n) considers the menu item language when deciding its active state. Thus, your argumentation of need would be obsoleted: Aliases and menu items have a language that can be interpreted correctly in priorities.

If there's even more why you state we need it, please tell me.

Do you need more information?. Do we can close issue?