For me, time-tested and formulaic are equivalent; and equate to a lack of surprises, at least for a jaded consumer of fiction.
I am a jaded consumer of Television entertainment. I know the formulas, often when watching a movie, hour long or half hour long show, I know who the villain is when they first appear. Especially if they look like a walk on that has more than one line that doesn't advance the plot; we don't have a friendly four line conversation with the janitor for nothing.
I know when the twist is coming, so I recognize it. Everybody knew doctor House's Fail-Fail-Brilliant Insight formula.
So most TV is formulaic to me, and I could easily be bored by it, but even when a show follows the formula, I can be entertained by the writer's originality in hiding the villain, or in the twist, or just in their pause-the-show-to-laugh-out-loud humor.
That is what I am entertained by, an original and unexpected surprise in the craft. It's clever, it's funny, it's surprisingly heart-breaking. For example, I was caught completely flat-footed by The Sixth Sense. It was formulaic all the way through, I knew there had to be a twist but couldn't figure out what it was. Then boom goes the dynamite! It was both obvious in retrospect and completely unexpected. I had to watch it again, immediately, to see if they cheated! Nope, not once. Legitimate props.
Formulaic will entertain some people, especially young people that haven't picked up on the patterns yet, and adults that are not very analytically minded so they don't realize there are patterns manipulating them. They want to be manipulated, that's the point of fiction. And that's the reason to use time-tested formulas.
But if you want something that is going to make a splash, you need to put some effort (or natural born talent) into creating satisfying surprises. I don't see much point in straying very far from the time-tested structures. There are several, it is not just the Hero's Journey. But it is important to realize that just like Campbell's Hero's Journey, that was not invented by him, it was a distillation of his study of thousands of myths in many cultures. It represents a common skeleton of stories that last and are retold for hundreds or thousands of years.
The same is true for the Three Act Structure and its turning points. (I am a fan of the Four Act structure, nearly identical but it split the 2nd Act in half.) It is the result of studying already successful stories, and distilling out their commonalities.
So it is saying "Successful stories have these things in common."
It is NOT saying "If you ensure these commonalities are present, your story will be successful."
You just increase your chances of having a successful story by loosely following the time-tested structure. (Loosely, because the turning points are averages, not hard and fast rules. e.g. an Inciting Incident should occur somewhere early, typically near 12.5%, but it can vary from half that to twice that, depending on what the story needs for it to make sense.)
Just using the structure doesn't guarantee anything. What will set you apart is NOT the time-tested part, but the originality, the surprise punches you can throw while working within that structure.