The reason I personally don't choose to put AW in my tank macro is that it inevitably goes off at a very inopportune time. Having Wrath up when a bubble wall would save the raid is quite bad in my opinion. As a general rule, Paladins don't have a lot of trouble with burst threat nor sustained, so I don't feel it's necessary for it to be up every cooldown. Not being snooty here or anything, it's just personal preference.