You were making some absolute assertions, so yes, I would expect you to have some actual examples based on real experience. Asking you what homework you based that on wasn’t rhetoric but simply a question because I know multiple projects using OpenSearch who’ve had no problems other than Elastic sabotaging certain clients. It would be useful to know, for example, if there was a certain class of functionality or performance challenge where the difference is significant.
We've already identified that the merit of a managed AWS (but really any cloud provider) solution is that you've already done your due diligence for that provider, and that alone far outweighs whatever other merit you might consider.
Some of the other stuff is what I might consider if I had to make a case for approving a new vendor, but this is an overwhelming barrage of rhetorical questions that makes it difficult to have a reasoned conversation about.
I mean, come on... what percentage of users depend on those features? Unilateral control over a product roadmap? Am I supposed to actually know these things when stating my opinion that OpenSearch is lame in comparison to the original ElasticSearch, based on my anecdotal experience of dealing with the two? Do you have those answers yourself?
As to the risk, a fair question. There's currently a threat that ES client libraries will reject a connection to OS (and I recall this has already been done for some languages). Not the end of the world but the only people who have lost out from the licensing spat you've alluded to are the users. The risks of onboarding Elastic as a new vendor or self-hosting are well known and part of the usual discussion of trade-offs one will have.