Meaningless yet complex stories are ones where there’s no simplicity, everything is about and is presented as some giant mess that becomes unrelatable, often as there’s no hook or way to get into it. If you can’t sum up a part of a tale simply it may really be just a pile of stuff, only complex as you’re playing conceptual Jenga.
Simple and shallow stories where there are hooks, but little depth. There’s little connection or meaning, so there’s not a lot of “there” there. In extreme cases its just a pile of tropes.
I don't think anyone ever sits down and says, "I will tell a hopelessly complex story," or "I will tell a shallow little story." Those things are by-products.
The first is a by-product of ambition, too often expressed as just making things bigger longer faster harder deeper MORE. We think the only way to make something profound, important, absorbing, is to pile things on.
The second stems from being clever, or rather from thinking that cleverness is the end-all of how good stories work. Both present incomplete pictures, but it's easy to believe things created on those veins are models to follow when there are so damn many of them and some of them enjoy remarkable commercial success and cultural influence.
I think I have experience with both of these extremes. The first one I veered close to in an early outline for Flight Of The Vajra. There was a lot going on, but it didn't add up to anything; it wasn't about anything. It was more about the accrual of elements than it was about a simple, straightforward need that becomes the driver for a great many complicated things.
The second one, simple and shallow, was another of the manifold problems that beleaguered the now-shelved Palace Of The Red Desert. Instead of a simple story, I ended up with a simplistic story. I haven't yet found out how to back out of that particular dead end, but someday I will.
At the heart of every great story is someone's driving need, expressed in any number of ways. If we have to say that one thing is what's at the heart, it's only because any story, any process of storytelling, starts with selectivity. Who is this story about and how is it about them? Where do they want to go, and where do they in fact ultimately end up? If you nail that, you don't need to be either outsized or clever.