By its very nature, i18n is less tied to a particular language than 'internationalization'. 'Internationalization' is a generic english word for making things international somehow. i18n specifically refers to making software more accepting of different input methods, fonts, text orderings, etc. Far from being an abbreviation, i18n is a word in its own right, with an international meaning.
Think about www. www means the same thing everywhere. No-one localizes www so it can be expanded to a sensible phrase in their native language1. It's just www. Because i18n means the same everywhere, it is possible to search for it without having to translate the term between languages (even the trivial case of American to English is a one letter change), and without having to wade through instances of the word being used in passing2.
And yes, i18n is tied to a specific culture - the programmer culture of the people who would actually carry out i18n. So what if the term is obscure to a layperson? If the l10n's been done right, they're never going to encounter it.
1 - Not even the French, although some tried to convert it into their acronym style - w3 instead of www.
2 - www.internationalisation.org, for instance, has nothing to do with i18n.