It has happened in.... I'd say 4 games in the last 8 years I can think of quickly.
You had apprentices and sidekicks or you raised monsters? You combined them. I've seen the second on plenty, and former pretty much never.
And if you're going to keep making up words to violently shove into my mouth, what's the point lol? I obviously didn't say anything about "death metal covers" so don't pretend I did! That's just really sad and flabby argumentation that show you don't actually have a point.
But it does work as PART of a campaign.
Does it? It's literally the endgame for the couple describe, not "part of a campaign", unless you just mean the end/epilogue of a campaign, in which case, sure that sort of thing has been the end of campaigns since time immemoriam. Coffee bars are just update on taverns!
Right, I'm not sure what your definition of Twee is, other than insulting whatever art it is you don't like. But I can say, it sounds like cutesy... and there may have been a handful of those pictures.
It's excessively, aggressively cutesy beyond a certain threshold, and you're being a bit of a hypocrite to complain about me using that term, give you throw around terms plenty for stuff you're complaining about. If you don't understand it, maybe ask for an explanation instead of making one up?
And the "kid art" is on you. Twee doesn't have to be "kiddy" in sense of actually appealing to or genuinely intended for children (indeed, it very often isn't). Lots of children don't even like it - see the success of countless artists like Quentin Blake who draw for children but strongly eschew the twee - indeed most better children's artists do - there's nothing "twee" about the Gruffalo, for example. It's well-judged rather than aggressively cutesy.
So far I've seen a bit of cutesy but not excessive art for 5E, a lot of art that's neither cutesy nor edgy (which is fine), and a little bit of outright twee art, and a couple of pieces which are borderline. What I haven't seen yet is anything scary or menacing - the DMG could have been but instead went for using D&D cartoon characters.
I know this seems to be very difficult for you to understand, because you seem to be actively looking to be mad about what I'm saying, but my concern is more about future direction. I don't think it's sensible for D&D to triple-down on being cute. Has it done that? Not yet. But a relatively small change of tack could send it there.