That is actually how it goes, though. The WWDC opening keynote is the typical Apple computer user's best look at what's coming up. It's not not technical, but it's very much deliberately made to be approachable to non-developers.
Whether you agree with this choice or not, it's the way things have been for at least as long as I've been watching (which is over a decade).
Think of it by analogy as the keynote for the conference is like the back cover summary of a book.
Despite technically being part of a developer conference, the intro keynote has always functioned more like a consumer-focused annual hardware and software update for Apple device users.
Hence things like the ever-present use of things like impressive-sounding "marketing benchmarks" that wouldn't pass as up to snuff on slides in a room of developers.
And also the very high level of abstraction so that non-technical users can understand the major updates — that's not exactly a trait one would use to describe a developer conference.
