Yes, there was a time when some opus with adult-oriented, quasi-profound lyrics such as "The Windmills of Your Mind" could become a big chart hit.
However, if you say "Windmills of Your Mind" to me, the first thing my mind conjures is Obi-Wan Kenobi's rendition of "When the Force Controls Your Mind" from a 1978 issue of MAD Magazine which gave us "The Force and I: The Star Wars Musical," written by the incomparable Frank Jacobs, arguably the most quoted poet of his generation.
What was great about the parody was that I was able to sing along to Jacobs's lyrics because of my over-familiarity with all that "wheel-within-a-wheel" schmaltz -- a familiarity engendered by all those occasions when some super=serious actor like Vincent Price would go on an 1970s variety show and "sing"/recite it a la Rex Harrison (Rex's son Noel Harrison had a charted version of it). Perhaps it wasn't Vincent Price; however, I do remember him guesting on "The Carol Burnett Show" with a rendition of "Desiderata" ("you are a child of the universe...").
Back to Frank Jacobs: I was in seventh grade at a point in the mid-1970s when MAD saw its highest circulation. Virtually all the kids in the schoolyard were quoting and reciting Jacobs's song lyrics, poetry, and nursery rhyme parodies. Thus, my appellation "the most quoted poet of his generation."
Say what you want about MAD's juvenile sense of subversion ... but Frank Jacobs did bring a modicum of literateness to its pages.
Here's a YouTube link to "The Windmills of Your Mind" in Polish: