Failed Saving Throw
Explorer
Lets face it, there are different needs. The only thing that was a more or less dubious decision was the GSL.
But lets face it, Most peolpe want crunch. Fluff is something that is independant from editions. So, if someone wanted to create a book full of fluff for 4th edition, no GSL can prevent him to do so.
And even with GSL adding fluff is not forbidden. If I have understood it right, changing crunch is forbidden and may only be referenced, not copied. So a monster fluff book which covers most monsters in MM1 and 2 could be done...
but will it be profitable? i doubt it.
I suppose it could be, if you created a specific setting and then release a fluff book of how monsters fit into that world. I dunno. I would approach something like that with skepticism, but it could be interesting. After all, Paizo has basically done a version of this concept twice with good results.