I'm fine with the PHB classes. They can even take another couple years before releasing.
The only thing that I'll never understand is the releasing classes and updating the first act sets them back on finishing the game... all of that is part of the final game, yeah? Like I've said a hundred times. They need to prioritize getting the base stuff out first since it can all impact later act layouts, world building, quests, etc.
Narrative, quest branching, general planning and locations can be done in reverse, but everything else?
Rather, what takes the most time is cutting out what shouldn't be found in EA.
It isnt surprising that classes dont have high priority.
It is more important that all content is completed than adding another class that will have little impact on the rest of the game.
Creating locations, quests or models is much more time consuming than a new class.
Another thing is that they certainly have most, if not all, specific dialog lines for each class.
And what shouldn't be in EA? I can't imagine anything in an introductory act that shouldn't be in EA when the goal is feedback and testing. Or do you mean removing content that people could datamine?
As for classes having little impact on the rest of the game, I'd wholeheartedly disagree. How they function mechanically could absolutely have a rather large impact on the design of encounters, locations, placement of objects, size of areas, etc.
If you don't have that stuff ahead of time, you either find yourself needing to completely rework that material or saying screw it and having shit encounters. Though to be fair they have the more important classes in for those designs right now.
I'd argue that classes, balancing and gameplay mechanics (like leveling) are the most crucial elements in the EA, followed by feedback on things like how companions were altered.
I'm all for this game taking years before launch and them spending time making it the best they can, but I'm certainly not for a single class taking 6 months and an entire year passing without another companion being added. At their current rate it'd take until Oct. 2023 for all of the classes in EA and even then that gives zero time for testing and feedback on that last class.