With my opinions of the current state of the game and the future expansion aside...

On a definition side of things. Blackmail is more closely associated with extortion. "of demanding payment or another benefit from someone in return for not revealing compromising or damaging information about them." so I wouldn't align Unsubbing, boycotting, or protesting as blackmail. It is really more of a way to show displeasure of a product or service. Some may be more vocal about it than others but it really doesn't fall under the blackmail umbrella.

With that said, It is ultimately the consumers right to stop paying for a service if they do not feel that it is worth their money.