It may also have to do something with scope. In 2000-~2010 Apple was basically and iPod + UNIX desktop company. The iPods did not spectacularly until the iPod Touch/iPhone, OS X had a relatively narrow scope: a UNIX system supporting a small hardware range, with a nice modern display server, and good object-oriented frameworks.
In the last years their scope has expanded immensely, both hardware-wise (iPhone, iPad, Apple Watch, Apple TV, now HomePod) and software-wise: AirPlay, CarPlay, Homekit, HealthKit, AR, Apple Music, Force Touch, machine learning, Siri, Handoff, Airdrop, Emoji with face recognition, etc. A lot of these technologies work somewhat, but are glitchy.
Of course, there are many times larger than the Apple of 2007, but managing an extremely broad palette of technologies is difficult. Especially when you want them all to produce something in-sync in the autumn. In some sense, Apple may have spread themselves to thinly.
I think think that we would be better served by an Apple that was more focused on core technologies and would let the third-party ecosystem focus on applications. Or perhaps completely separate divisions that would focus on macOS, iOS, and hardware. Or shipping features when they are done (rolling-release style) rather than one big drop every year.
At any rate, their current direction is hurting core, traditional use cases for Apple products. E.g. Preview.app/PDFKit has been really terrible the last two releases, to the point where I can barely use it for previewing my lecture slides, etc. Basic technologies like PDF rendering used to be stuff that they had nailed down extremely well.