Why couldnt the wood elves do that in Skyrim?
Because I see the Bosmer's cannibalism as more of a local custom. It's something they practise religously in their homeland because they are not allowed to touch the plants that grow their and can only eat meat from animals and each other. But in other provinces I'm pretty sure cannibalism is extremly taboo and illegal so no Bosmer would practice it outside their homeland, especially because they have no reason to do it since it's OK for them to eat the plants that grow outside their forests.
Also cannibalism doesn't really seem to mix well with the medieval fantasy setting of an RPG game, at least not from a player character's perspective. It fits more with the Fallout series because it's set in an apocalyptic world where food and water is scarce and humans are having to eat unsual sources of food just to stay alive.
If people really want cannibalism in Skyrim then I'm not going to argue with their opinion, but I personally don't think it would fit the game. :shrug: