> Without putting blame on anyone, this does show a fundamental issue with the open core model.
The "fundamental issue" isn't a matter of blame, it's entirely intentional. The problems that it can lead to for consumers is that they might have to host and maintain their own patches if they prefer to write than to pay, and otherwise if they can share the responsibility for that maintenance with a group of people, they've pretty much created a hostile fork. For the projects themselves, the problem is that people will create hostile forks if your prices aren't low enough.
As far as I can tell, the solution for open core stuff has been to pour most of the effort into the proprietary features and support, and to market to enterprise. That way the sky is the limit on price, and hostile forks that add the features you forbid can't catch up with you, at least in the enterprise market. This isn't always successful, but it makes sense to me.
There's no spirit of Open Source. Open Source is software that you're allowed to use, copy, modify, and distribute freely. It isn't required to be good, it isn't required to take any contributions, it isn't required to take any suggestions.