Sounds to me like you've gotten two true things conflated together into something untrue.
AIUI, they did not originally intend to make 4e so soon after making 3e. Instead, they intended to go full steam ahead for 3e, but it ended up having...well, a lot of holes. So they patched up a few of the obvious ones (while leaving most of the actually
serious ones), and called it 3.5e.
Now,
once they had published 3.5e, they did in fact want to immediately begin ground work on a new edition. Internally, it was referred to as "Orcus," and you're correct that this new edition failed to cross the finish line properly. Instead, they published it...as
the Book of Nine Swords. That's why those classes all have such a coherent, singular focus. They were the first draft of the team's efforts to fix the problems with non-casters in 3.5e. It just wasn't working out the way they wanted, so they turned it into a 3.5e product and went back to the drawing board, taking lessons learned from "Orcus" and applying them to the new project, "Flywheel," which became the seed of what we call "4th Edition" today.
You can read about this stuff here. It's somewhat interesting.
It
was rushed out, but that has little to nothing to do with how much errata it received.