[Disclaimer: this is pure conjecture and represents my opinion only; I'm a Google outsider.]
For a while, "AWS" and "the cloud" were practical synonyms; it was very rare that anyone meant not-AWS. In my opinion, Kubernetes is a major piece of Google's strategy to turn that tide and improve their marketshare.
Does throwing "a large team of engineers" at a problem typically result in something that's "as easy as possible to use"? "Design-by-committee" is not a term of endearment.
A sibling comment at https://news.ycombinator.com/item?id=18958077 notes that "there are a ton of nicer UIs for Kubernetes", but that they're sold separately as proprietary PaaS platforms. Even if we pretend like GCP/GKE isn't one of them, Kubernetes-The-Platform will be impacted by the interests of its primary vendors and advocates, whether or not certain teams at Google are keen to admit that.