The problem with Canon is they are still lagging behind in bringing lenses and cameras through the development cycle into the real world. This is a common problem when companies become huge and think they can either do no wrong or believe that people will wait for whatever they eventually come up with. Many companies have done this like Nikon and we know the story.
Take the 200-400f/4. It was pre-announced, marketed and hyped to death for what, 2 years?, before it became widely available. By then, I had tired of the relentless push and actually looked at what I needed, and got a 200 f/1.8 instead and relied on the smaller sensor size to gain added reach.
Speaking of lagging behind, Canon users have had an AF 35/1.4 since 1998. Nikon finally introduced theirs in 2011. Canon users have had an AF 24/1.4 since 1997. Nikon users had to wait for theirs until 2010. Of course, these things balance out. Nikon has offered some lenses that Canon hasn't (28/1.4).
But there's no need to imagine that they think foolish things, like that they "can do no wrong". The reality is probably more like: no matter how big they are, they aren't big enough to make everything that everyone wants exactly when everyone wants it. Each company has a finite number of engineers, production lines, storage facilities & other resources. They are always prioritizing something to get done now, something else to get done next year, and so on. The result is in fact a stream of new & better products, though not a fast stream. Some products take a long time to develop and test, and some buyers will inevitably be frustrated no matter what they build.
In the same way you looked at what you "actually needed", the manufacturer looks at what it actually needs to produce. Canon may have decided that a $12,000 200-400mm zoom wasn't urgent, and could wait until it was tested and refined a few more times. Or they may just have allocated key resources to other products, which then got made and satisfied other buyers' needs.