I would argue that making Kafka more approachable and easy to deploy and use out of box is creating value for the developers, because it helps increase potential user adoption (and therefore increases the potential open source contributor base)

I agree. We started using Redis with AWS' managed offering (Elasticache), then migrated to running it on our own once we were comfortable with it. I can imagine the same path for Kafka use.

Open-source software is free, that's the point. If you wanted to make money with it then don't make it open-source. This entitlement is just silly.

Many vendors make money by selling services on top, and there are at least a dozen that offer managed Kafka right now.

operations could be headaches tho. I always think AWS as seperate operation contracto teams for running large scale distributed softwares

Then you couldn't run it on Linux, as you'd be unable to relicense the storage system that is the kernel file system or storage drivers from GPL to SSPL.