Early employee of CoreOS here. I wanted to float a few ideas out there for discussion.
First, while etcd did get a bit more complicated over the years, it stayed relatively stable compared to Consul. This was a point of pride of the etcd team and why it ultimately was picked for Kubernetes. Yes, a gRPC API is not as easy to use as HTTP, but this gained massive scale for Kubernetes when it was released. Something like a 10x increase in the number of nodes in a cluster, without changing any Kubernetes features. Just enabling etcd v3's gRPC API. That's pretty awesome.
As a member of the product team, I think we could have made different choices that would have massively impacted the ecosystem. Consul might not exist today. We did not want to add in a DNS server to etcd in order to keep it lean and focused. We had an integration with SkyDNS, but it wasn't on by default. This birthed Consul and its built in DNS server for service discovery. Consul is very popular so clearly this was the right move for some consumers. Kubernetes didn't need this, nor did Container Linux for its update coordination. For us, having this possible on top of etcd was the right trade off. Consul has added a complete service mesh into the later version. Again, etcd has stayed lean and focused. I think you are focusing on pebbles when you take in the overall ecosystem.
Would you rather etcd have turned into Consul's breadth? Would it have been forked?
The second point is around the success of Container Linux. I only include this because I am proud of it. We updated and secured a fleet of machines that measured larger than some cloud providers. That is a huge impact on the container and security ecosystems. Flatcar Linux and Fedora CoreOS remain as successors, along with other projects like Google'c container optimized OS and I think AWS announced one as well.
This work continues at Red Hat on OpenShift, etcd, Fedora/RHEL CoreOS, and tying Kubernetes more closely with the OS to keep the combined whole secure, up to date and successful for engineering teams shipping software.