Interesting point about the tone because I think I'd sort of subconsciously noticed the Trine series heading in that direction (the original was dark and vaguely apocalyptic, the second was sort of neutral, but trine 4 was pretty much exactly as you describe) but it didn't occur to me that this was part of a wider trend. But, personally, I don't think it's necessarily a bad thing in the context of modern developers. I would actually prefer devs move back to more simplistic good vs mild evil than mire themselves in endless shades-of-grey or everyone is bad stuff. Morally ambiguous settings and stories require skilled and intelligent writers, and flat out "everything is shit and everyone is a bad guy" settings & stories require writers who don't give a fuck. But if you take some mediocre writer, and they try to do some shades of grey morally ambiguous stuff, they'll end up writing pretentious garbage, and if you take someone who's worried about offending people, and they try to write something grimdark, it'll just be bland and shitty and not very engaging. I would prefer writers like that stick to lighthearted Disney stories because those are a lot harder to fuck up for those sorts of writers.