Nerfed is one thing. I started with Dark Angels, nerfed is the default for me.
With CSM in particular, folks are more upset over armies they build becoming invalid or impossible to do without counts-as. Me, for example, my Alpha Legion had half its number removed from the Codex when 4th dropped, so I got rid of them. When the current book came out, I got a little excited and built up another army. I've since sold it, because I want to play Alpha Legion instead of counts-as Red Corsairs, Black Legion or Raven Guard.
People who are passionate about the game are going to complain about it. Call them optimists, hoping GW will eventually do better, rather than just quitting. People have been complaining about this and that for years, don't you think it's a little silly to get worked up over what other people think? You could really turn that concern into feeding those starving children.