There are some nice advantages to being able to use /focus to control all your targetting, to be honest. I use it all the time when I'm raiding if I want to be a little bit lazy (or just make sure I don't break CC). I love to focus another player (mage/rogue) and just let that person designate my targets. I also run my 4 shammies by themselves, with my prot pally, with my boomkin, or sometimes with a friend who is tanking (think heroics) -- hard-coding in every possible scenario gets tricky.

I am impressed with this technique, but I think there is some merit to using /focus if you can get away with it (like a lot of class combos can, to be honest).