I don't think anybody says the "voluntary" thing is a fact, it's always been just conjecture from what I've seen. It has about as much leg to stand on as the opposite imho, since nobody ever said anything about her feelings on the matter lol. Just Zeus, Hades and Demeter. The current generation just so feels that the mother might have been a bit overprotective, considering the death goddess part, which is afaik real.

So the story was always about an arranged marriage against the mother's wishes with a creepy guy. What people interpret Persephone's feelings were on the matter will change generation to generation imho, as they aren't recorded. And since the older generation is currently viewed as extremely backwards (and not just currently, this has been going on for a few decades since the whole sexual revolution thing), right now people interpret her mother as being wrong. She very clearly changed and embraced her role after all? -> so she was different and couldn't be herself at home. Maybe a few generations earlier people interpreted it as a predator taking a helpless girl with the help of the authorities and the heroic mother fighting against that. It just doesn't really fit into the current culture.

I can't find any of that "voluntary" factual claims that you talk about, other than some astrological mumbo-jumbo, but I seem to recall one story that started with something like "everybody forgot that she went willingly", and iirc, it was a fanfiction. It was written in a very decisive manner but didn't pose as actual fact, I just can't find it right now (and it's driving me up the wall, will keep trying). Was going around a few years ago. Not possible to find anything on AO3 now what with every fandom having a hades/persephone version of their main pairing that then shows up on search lol!

...but that should also tell you how much people are into that new interpretation of the story.