I happen to like arms more than fury. I happen to also believe that its rotation/priority system is tighter and more involved than fury's. Therefore, I think a lot of the problem lies in the fact that many fury warriors aren't used to being gcd capped, and having to maximize it. Much less keep up buffs like lambs to the slaughter, or having their spec cooldown prevent their other cooldowns.

That said, I still do a few thousand more dps as arms (with gurth), than I do with fury (with 2 gurth), without spending the headache on stance dance macros to maximize uptime in berserker stance. To the extent that I was beating out my fury dps without realizing that I had fury glyphs in my arms spec. (I had gone fury when I finally got a second 2hander, on account of pre-tier 13 fury dominance)

However, I also was a tank with an arms offspec (could not acquire a second FL 2hander) all of FL, and so had a decent amount of practice. Therefore I completely agree with the posting of an arms article for spec changing furies.