Because there are people that seem to be unclear on the subject:
The reason people type "l10n" and "i18n" instead of "localization" and "internationalization" is because the words’ length makes them difficult to type. Tech communities are willing to put up with this ungainly and opaque shorthand for the sake of our wrists.
In spoken English, "EYE-eighteen-EN" is not easier to say that the expanded form. Pronouncing the keyboard shorthand does not imply that speaker is savvy or in the know. It should not be done.