It's always been a pet peeve of mine when someone prescribes very specific "rules for storytelling" to a work, and chides it for not adhering to them. I think One Piece is probably among the most compelling worlds I've ever encountered in fiction, by virtue of how we only have tiny glimpses at its history from time to time, while the day-to-day focus is in fleshing out its present day. Every time the Straw Hats hit a new island, a brand new culture is splayed out, one we typically had no real inkling ahead of time. Huge amounts of new characters, new conflicts, new concepts that suggest an actual living and peopled place. The world grows enormously with every new island, and I love that. The aren't just stops along the way, blips in the Straw Hats personal journeys, but rather fully-developed microcosms that develop the
world more than anything. The story of the Straw Hats is really just a foil so we can travel through the grand line and see what this place is like.
When there's a reference to the void century, I consider it a perk, not something I just want to push through all the other content to reach. I know ahead of time how huge this journey is, and I don't want to know everything about the secret history of the world until the end. It's a great little macguffin, one that would lose all of its joy if they gave us too much info too fast. Hell, Luffy said pretty much exactly that when they were about to just be told the whole thing straight-up. If they don't figure it out themselves bit by bit as they go, what the hell kind of adventure is that?
Basically every main arc has hinted at things, but those things are never the
purpose of the arc. It's the conflicts of the present day that are the real story of One Piece, the void century is just a sidestory that will pay off only near the very end. And that's really how I'd prefer it.
I agree that plenty of the characters are quite one-dimensional and don't exhibit a particularly large amount of growth, but I see them mainly just as entry points for telling stories about the world. We certainly have pretty amazing character stories in there from time to time, but I think they're secondary. These crew is here as our guide through whatever story is being told about the world and its cultures. If there were never ANY good character moments I think that would be a failing, but I certainly don't think that's the case in the least. Plenty of stories about the crew's pasts', and things like Luffy vs Usopp throughout Enies Lobby, these keep the characters interesting.
You describe Bleach as "character driven," and that's fine, but I don't see any reason to chide One Piece for being constructed in a very different way. They're just different modes of storytelling, and while I like the deep focus into one specific kind of concentrated arc and threat in Bleach, One Piece's far wider-spanning arc is equally compelling to me, just for completely different reasons. One has a focus on a couple well-defined groups in a well-defined conflict, while the other stretches its plot across the entire planet. Bleach tells us about Ichigo and his life through its conflicts, the other tells us about a world and its people through the lens of an adventure.
I like 'em both. And Naruto, too, which kind of rests squarely in between One Piece and Bleach in terms of what it's trying to do! It's okay for different things to do things in different ways! While there may be such a thing as bad storytelling, I don't think any of these are really that. They just approach the telling of a story in different ways.