That said, after the last four months I've had of trying to get Route53, API Gateway, Lambdas, ECS, VPCs, Cognito, DynamoDB, S3, CloudFront, etc, etc running in CloudFormation I really can't imagine it's worse under any slightly involved scenario.
k8s definitely helps with the "all my apps stuff in one place that is easy to see". There are some pitfalls to avoid though. Don't use helm, it's bad for your health. Avoid deploying your own k8s cluster unless you really need to, just use GKE. Avoid custom resource definitions unless they are well supported, migrating off them can be hard - prefer tools that look at annotations etc (like external-dns, cert-manager and friends).
Of course things get difficult when you need statefulsets to run things like Kafka/ZK and friends but it's definitely possible and they run well once setup.
In my mind k8s is the only option right now that doesn't result in man-years being wasted on pointless AWS bullshit.
In the meantime, because you must install Helm into every namespace in your cluster into which you desire to install charts, it's a massive resource hog and security risk. Charts themselves also need to be hosted somewhere, so you end up needing to install Chartmuseum, Harbor, or Artifactory (if you didn't have Artifactory already), and they have their own operational costs.
I'm in the same boat where I avoid helm if at all possible.
That checkouts a local copy locked at a specific version, which you can bump easily, and allows overriding the template definitions on your side.
No need for additional infrastructure.
There are plenty of examples on github/gitlab for most of the services you mentioned. Like most programming languages, you need to separated the wheat from the chaffe; 99% of the CF publicly available sucks. Hit me up if you need help.
The problem is I can't give it directly to developers. I don't want to be constantly writing/maintaining abstraction layers over CF to make it half decent. You may as well use Terraform at that layer of abstraction because at least it frees you of some lock-in and has more sane state tracking (which too is pretty abysmal but we aren't talking about a high bar when comparing to CFN) but I digress.
You seem to be missing the point here, it's not that you can't do things with CFN, you can. The point is k8s allows me to administrate a system that puts all of the machinery behind a nice unified API that all of my developers can consume without requiring an SRE to make every change and be there to hand hold them through setting up a new service.
It may be more complex but that complexity quickly pays off with the amount of stuff now solved in a self service manner. Sure some stuff needs to get much better, there are poorly understood primitives like Service and Ingress that could do with better docs to help explain to devs when you should use one and why.
Overall things are much better than the "AWS as an abstraction" way where everyone is clamouring to use some half baked AWS garbage service rather than just doing the old tried and true thing (screw Kinesis for example).