Understanding about what? People told him they started watching and continue to watch his channel because of his gaming content, he's free to do whatever the fuck else he wants, people are giving him valuable Feedback that they don't like or appreciate his new kind of content. If he continues putting out content that they don't like because he's "sick of the other stuff" he got famous with, they're likely going to leave him given time.
It's more than that given that this has happened to many, but they didn't flip out and exclaim that their audience are beggers that shouldn't be choosers (Something I'd call Joe and everyone else that does this as well, they're very lucky they're able to make money of of this sort of thing, much less
good money), they were either honest and worked to provide decent content while slowly shifting their "show" into territory they wanted to do, like how Rolfe has gone back to his old love of movies mostly, or they transitioned while trying to mask the transition in something more entertaining, like Pewdiepie effectively doing tell all videos about how he hated the forced amusement crap as well as straying increasingly into more mature, controversial stuff that goes well with the fact that his audience is moving into young adult territory if not being 20 somethings that no longer find his tourettes antics amusing anymore (or at least soon will as Rolfe was wise enough to see with AVGN).
If he put out a calm, reasoned video of him saying that as much as he'll try to give what people want, while doing what he wants to do, like Rolfe did with that video, we get this whining. It's better to keep calm and work on producing the stuff you want to make while retaining those that will continue to like it and accepting those that stop watching, than it is to bitch and lose both those kinds of people.
If he keeps going he will get what he wants, his subscribers will drop, but it'll be a lot less than hundreds of thousands he cut it off at.
I think a problem with Joe might be that he doesn't like not being liked, and if you're going to effectively end the glory days of what made your famous, it's going to cause a lot of dislike and you'll receive a lot of it until the transition is done and people have to live with it.
That or he's a lazy fuck and just wants people to keep giving him money while he doesn't want to work as hard as he once did...
Anyone wanna bet whether someone's going to make one of those Post-Mortem videos for him in like ~5 years?
What first came to my mind, actually.