I think part of it is that standards keep increasing. Compare this demon concept art from Warcraft 2 (1995): http://vignette2.wikia.nocookie.net/wowwiki/images/c/cb/Daem... to this one from WoW: Legion (2016): https://s-media-cache-ak0.pinimg.com/736x/56/f2/7f/56f27f98a...
There are probably a lot of artists that can execute at the 1995 level who aren't employable in 2016.
