Well, people were and still complaining about UCP, might not be apparent here because blog posts has been disabled, but on other wikis, they're just complaining.
Well, not that I like UCP either, but you are obviously still using it.
CC had to migrate, there was no other option, though I was surprised it wasn't the last one and frustrated that there was no pre-migration banner. Mendes2 said that the informed the admins instead, but that's unrespectful toward the active users in my opinion.
My understanding is that the lack of a pre-migration banner was typical for large active wikis since the admins would be contacted in-person. Basically, if you wiki got the banner, it meant Fandom didn't have your wiki on its top priority list.