What is your source on this?Rumour has it the developer in charge of Druid and Priest left the company, which would explain the absence of anything substantial.
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Different developers are essentially given free reign to develop the classes. The hunter and shaman one does that by being active in the forum's, answering questions. The rogue one I hear is fairly active on the discord, just not in making blueposts, and the druid and priest one is supposedly no longer with the company.
It's extremely annoying to anyone not playing one of the lucky classes like hunter, but at least it makes it blatantly obvious which developers get praise and which ones don't, and how to fix it.