Out of this whole thread, what bothered me most was the attempt to make opinions a fact.
Fact Is, there's no absolute metric for objectification of "fun", ever.
This is flat out wrong. If I poll everyone on TMD and ask them "Do you consider X to be fun?" and tabulate the results, I have generated an objective measure of fun. Now you can debate my sampling method, examine bias, argue about applicability, etc. but the very fact that you can do this makes it objective. If it were subjective, you would not be able to argue that. I can't argue with you on what you find to be fun. I consider the World Cup entertaining, but that has no bearing on whether you enjoy it. And the term "absolute measure" has no scientific meaning in this context... I'm not even sure what you are trying to say. It sounds like you are trying to hedge on semantics.
On a general note, the users saying that "fun should never be factored into B&R decisions" are making emotional appeals to an arbitrary sense of justice and not dealing with reality. It's pretty clear that Wizards takes fun into consideration when designing sets and managing formats. It's a game, not a court of law. The purpose is fun, not justice. Discuss cards appropriately on their own merits and effects on the format. Don't simply restate platitudes.
Edit: @Smmenen I actually think the restrictions of Gush, Mentor, 2 Delve spells, and 3 lock pieces have created more entertaining and interactive games with more diversity in deck selection. Hinging an entire formats health on one card seems a bit of a stretch.