Why does "information" not have a plural form?

Solution 1:

Because there is no such thing as a plural meaning of information. It’s not a count noun. Information is a mass noun, like air or water or rice or flour or courage. Or news.

You can only have less information, never *fewer information.

You can only have more information, never *many information.

And you can only have information, never several of *them.

Information is an it, never a they.

Solution 2:

The answer to this depends on what you mean by English. In native-speaker norms, information is a non-count noun, so the convention is that information is both singular and plural. However, it is very common for English as lingua franca (ELF) users to add an 's'. This is viewed as 'error' by native-speakers (or those affected/infected by their notion of standard or norms, e.g. teachers, examiners) or traditionally classified as interlanguage (an incomplete state of language proficiency) or fossilised learning. A different interpretation is of the addition of 's' as a regularisation strategy or as Jenkins (2011) describes it 'redundancy reduction...[something] towards which the virtual English language is already predisposed.' In this regard, ELF speakers seem ahead of the curve (and many argue are already the drivers for change in the language).

A perfectly valid question for an English learner might be, why learn an exception such as mass/count noun plurals, when every speaker I meet will understand what I mean?

Solution 3:

Most uses of information are non-countable. However it should be noted that talking of a "countable noun" or "uncountable noun" are really an over-simplifications; nouns aren't countable or uncountable as a word, but as a sense.

One sense of information is a statement about criminal activity brought before a judge or magistrate. This sense is countable, and in this sense you can indeed have two or more informations.