alt Hacker NewsThe focus on clarity of thought is a modern shift, or at least the "modern preference". Hemingway was a big proponent on short, direct sentences and few or no adjectives.
In the 1800s and early 1900s, complex sentence structure signaled intelligence for both the author and reader. It was a form of entertainment, in a way, when books were few and nights were long. Try reading Henry James for an idea about what this looked like in practice. Shakespeare is another obvious example of "heightened language" besides archaic words the play are written in iambic pentameter and the spoken text is far from natural (yet incredibly precise).
> the play are written in iambic pentameter and the spoken text is far from natural (yet incredibly precise)
(Iambic pentameters are 10-syllable lines with alternate syllables unstressed and stressed, like "if MUSic BE the FOOD of LOVE ...", the so-called heartbeat rhythm)
Shakespeare actually used a variety of different styles to demarcate different characters, moods, etc. As a very rough rule-of-thumb in Shakespeare, posh characters speak in iambic pentameters, commoners and clowns speak in prose. In A Midsummer Night's Dream, for example, the Athenians speak in iambic pentameters and the clowns speak in prose. When the clowns put on a play for the Athenians, the clowns and the Athenians swap speaking styles, so the Athenians make snarky comments in prose (just like a badly behaved audience) on the badly rhymed acting of the clowns. The fairies, meanwhile, speak in trochaic verse, so their king and queen sound stylistically different from their Athenian equivalents, almost like Shakespeare has given them a foreign accent. When two characters are arguing, the ten syllables of a normal line are sometimes split between them to emphasize the back and forth nature. If a character is flustered or annoyed, their lines may be obviously different from the 10 syllable norm, again to emphasize their mood.
For actors learning their lines, the syllable counts almost act as stage direction hints: if they aren't 10 syllables, then some mood or other needs to be taken into account.