Now we can choose our preferred language from [[Special:Preferences]] for user interface. In the same way if we can select Language of Namespaces also it will be more useful.
For example someone from en.wikipedia.org (or any wiki) make an account with ml.wikipedia.org (for references, for bot, etc.) he/she can set [[Special:Preferences]] for his/her preferred language like en,ar,fr,de, etc. then all the system messages and user interface will be displayed in his language.
But still the namespaces will be displayed in Malayalam!. There are equal main namespaces available in MessagesXX.php. eg: NS_IMAGE is equal to 'Image' (en), 'ചിത്രം' (ml), 'صورة' (ar), etc. If they can see the main namespaces in their preferred language then it will be more easy for them to select their search without confusion.