Remember that en:wp's "no original research" rule was invented for physics cranks. And even with fairly light moderation, arXiv features some spectacularly gibbering [[green ink]]. This will need some thought to create something that's actually useful to anyone, anywhere, ever.
A "free journal" would be very unlike our existing projects. The scientists need to be able to just take their entire publication process to a free platform-- with no other alterations in how they do things. Science is its own community, so it wouldn't be a project that 'anyone can edit', it would a project that does exactly what the existing process does, except for free.
And being free is inherently better. Nobody who spends two years of their life on a two page article wants to see it hidden behind a pay wall. Scientists really want to be free, they just need the right partner to help them.
Alec