Then he is an ass. I play Thousand Sons and I use the same list vs all opponents. Even at different point values the only difference is that lower values mean less of my units. Gearing your armies to play a particular army is lame in the extreme.
Holy hell no. The old chaos codex was a unorganized mishmash of rules that contradicted each other continually, had tons of options that were useless and no one took and, most importantly, had rules that enabled HORRIBLY broken armies to be made. The new one has its problems, I won't argue that, but it is a FAR better written codex than the old one ever was. The focus from Gifts/Skills/Wargear to actual units and models was a needed one I think. Yes I agree that they should have kept some of the fluff and rules the same but overall it is a much better codex to build an army with. And for the most part any fluff that you used to have and rules pertaining to it are easily matched with YOUR OWN choices when you build the army (IW and AL being the two that just can't be).