> yet it's incredibly expensive to develop SW
It _can_ be. At the same time some of the most used software in the world manages just fine without a company running paid subscription plans and locking free users out of critical security components.
ElasticSearch/MongoDB/Redis et al are trying a new model for how to create OSS with a company behind it funding all/most of the development. That's OK, and I'm super interested to see how it works out long term. But there are many many counter examples of similar sized or way bigger software projects that never needed to do this. Pretty much everything that those three databases depend on to be used in applications is OSS that never had a "paid subscription" locking access up. How useful would any of them be without Linux, or Apache/Nginx, or Ruby/Python/PHP/Perl.
My fear is that half-assed-OSS that does a _great_ job of "capturing developer mindshare" but a lousy job of securing free use of their software - is one day going to be the root cause of some _spectacularly expensive_ data breach, after which pointy haired bosses and less technical C suite suits are going to feel the full power of Oracle's golf-course-and-expensive-restaurant marketing army, and nobody in a company bigger than 10 or 12 people will ever be able to use any database with less that a half million a year license because "due diligence!" and "risk mitigation!" (and "Waygu steak with expensive whiskey" and "dirty free software hippies exposing you to data breaches!!!")