I thought, as someone who pretty much exclusively uses the discussion forums, that I'd weigh in on this one.
While I do spend an inordinate amount of time looking at the pretty pictures of the "for sale" animals, I'm not a buyer (sorry sellers), but I do "discuss" my animals, and I think that the discussion forums have several main points of value:
1) Getting advice on health problems someone has no experience with
2) "Newbies" asking for information on appropriate animals, housing etc
3) Displaying photos of the animals the owners are most proud of (and "oohing and aahing" at them)
4) Genetics discussions, particularly at Ball Python hatching time
However, I can see that the individual forums are getting less and less active. Whether this is a shift to other social media, or the result of a crackdown on bad behaviour from some of the more vociferous (and contentious) past members I can't say.
Whatever it is, if there is a need to reduce the real estate I do think that many of the discussion forums could be consolidated, as you say, into more general topics. I have no problem discussing boas in front of cornsnake people!
To me, the essentials would be ball pythons / other snakes, geckos /other lizards, tortoises/turtles, amphibians, etc, plus veterinary, general interest, and, of course, Hell.
Maybe a poll on the forums users value most would assist?