What is inflectional morphology good for?

In the tradition of Western linguistics, inflectional morphology is generally seen as a core part of grammar, and its continuous loss in those languages, for which we have long-term records, has typically been seen as a sign of decay rather than of useful simplification. We know of a number of cases, in which new morphology has been built up (such as the synthetic future in Romance languages), but this seems to be the exception rather than the rule. On the other hand, no one would assume that the very first human languages already exhibited rich inflectional systems: they must have formed in a complex historical development. In second language acquisition outside the classroom, learners regularly develop a form of language, called the >Basic Variety<, which is communicatively very efficient but has no functional variation in the form of verbs or nouns. What do its speakers gain, when they develop morphological means for case marking or for the expression of tense and aspect? This question is examined in this paper.