What is necessary knowledge for a single lexeme dictionary entry and why is language so complex if humans like 'ease of processing'?

Haspelmath establishes the difference between word-forms - just different instantiations of a single concept - and lexemes – which are sets of word-forms. Inflectional morphology creates word-forms and derivational morphology creates lexemes. A morpheme - or smallest meaningful constituent - sometimes has an abstract ‘meaning’ and really just serves a grammatical purpose. It’s interesting to see the parallels between morphemes and phonemes. Many morphological modifications have a basis in phonological changes. Furthermore, allomorphs relate to the concept of allophones we previously discussed. Morphemes change depending on a specific environment, but retain the same meaning and are in complementary distribution. For example, we pronounce the plural ‘s’ at the end of words differently depending on the phonological environment. Haspelmath also discusses compounds of complex lexemes. In general, the first member modifies the ‘head’ which is typically the second member. Sometimes the head is neither and the compound is exocentric, making it impossible to derive meaning from just the constituent parts. Sentences can be broken down first by the phrase structure rules in a word tree, and then further into morphological trees.

Slobin describes differences between verb-framed and satellite-framed languages. She argues that ‘ease of processing’ and cultural habits affect the narrative writing. Some trends include that multiple path satellites can be linked to one verb in S-languages, but V-languages are usually more compact. Also, V-languages pay less attention to ‘manner’ because another subordinate construction would be necessary which defies the tendency toward ‘ease of processing.’ However, satellite-framing isn’t the only thing that affects the use of manner verbs. In Russian for example, morphology - which Haspelmath discussed - also plays a role because it again affects simplicity. Slobin interestingly shows that lexical choices of manner are stable throughout all ages. I wonder why we don’t alter these as we grow older while it seems like other aspects of our language do change. For example, adults can obviously create much more complex and interesting sentences than a child can and they change other lexical choices based on factors like increased vocabulary and perhaps greater understanding of nuances in a language. Slobin’s article also makes me question why language is such a complex structure, if humans do in fact always try to opt for ease of processing.

The article by Atkins and Levins showed why semantically similar verbs can have different syntactic behavior and transitivity. They argue that externally caused verbs have causative transitive uses, but can also have intransitive uses. However, internally caused verbs describe events that happen from inherent properties - whether voluntarily or not - and not from external stimuli. Therefore, these are single argument verbs that can never have causative transitive uses.

All the information of word-forms versus lexemes, morphology, and different uses and semantics of verbs depending on ‘ease of processing,’ culture, language typology, and external versus internal causation applies to the real world because it determines what should be made explicit in dictionaries, and what is insightful for linguists, but unnecessary for basic dictionary entries.