> When you're writing / reading, it's much easier to parse complex sentences.

All other things being equal, I think this is only true because you can reread them at will and puzzle over them until you think you know what the author was trying to say.

Sometimes there's value in that. A good writer knows how to mix up the pacing of their prose, to organically guide the reader into engaging more fully with the parts that communicate complex ideas while the connective tissue disappears effortlessly into the background. But in the hands of a less skilled writer complex language is usually worse on balance: they don't understand that prose should always be economical, that less is almost always more, and many really do suffer from "the false impression that [they are] saying more than [they] actually are." Whether they're writing flowery romance fiction or technical manuals, they get high on their own supply without considering that writing is first and foremost a tool to convey meaning.

The "mercurial Spaniard" bit seems fine out of context. However, in context it had better be clear who that person actually is.