Are women really just deciding they want that shit or has society just reached such levels of open degeneracy that people lust after increasingly shocking things to stand out?
Regarding general degeneracy rather than the women-into-shota thing in particular (that one's pretty new to me, too), the opposite. Society is getting more prude, thus these things stand out more.
'There is no too young, only too tight, and tight is stretchable' is a sentence that stuck in my mind when a friend in a then-current anime circle I was in said it back in 2002 or so. As a joke, not as dating advice, sure, but I don't think he'd go for the same kind of humour today. 'If there's grass on the pitch, play ball' was a perfectly common saying in the chatrooms of the oughts, and I mean the normal, not the 'special' ones. Loli haet Pizza?, Rape: It's like saying hello in Japan? Funny maymays, and not just on the chans.
In most places,
you do not say these things anymore. Not without getting banhammered, at any rate. The medium itself is self-censoring more, too. Bare nipples in mainstream anime, once almost universal, are now almost extinct.
But the places were these 1990s and 2000s attitudes still persist stand out all the more as a result.
We as a society have become more prude, and subgroups who didn't get the notice thus stick out all the more.
Though this being said, there
is the additional factor of the vtuber fandom outside of places like here or /vt/ being
incredibly sheltered and so invested in feeling warm and cozy that it doesn't call out shit. So much so that anything beyond dad jokes flatly flies over its heads, and anything that threatens its cozyness, e.g. callouts for... well, basically anything, gets attacked.
Sometimes, this results in Calli Cancel Attempt #5762693 falling flat on its face
again.
Sometimes, it results in things like Iofi's/Pikamee's 'Nine to twelve year olds are the best!' exchange being memoryholed.