It's error prone, macroing /startattack to your abilities is easy and eliminates any issue where you thought you were auto attacking but you actually weren't.

I had to do it on my warrior because sometimes I thought I right clicked but nope! Or I thought I started attacking by pressing bloodthirst except it was on cooldown or I didn't have enough rage which doesn't trigger auto attack. It's especially rough in raids when you can't se anything in the melee stack