First of all, not every boss fight is "stand there and beat on the boss"

How awesome would LAotL have been on Putricide progression? Exactly.

Second of all, Selfless Healer is a nice talent, but you are being misleading when you suggest it is a damage increase, at least in the way you phrase it. Using WoG will NEVER be a DPS increase, just like it should never be a threat increase for Prot (which it actually may be in certain AOE situations). You get the 12% to off set the fact that you are not hitting TV with that HP, primarily. It's a carrot on a stick to try and lure badadins in to a talent and behavior that will benefit someone besides themselves.

Finally, re: rest of the conversation here, just because you can't hit GC immediately on proc doesn't make it a bad talent. Unless your Judgement debuff is falling off or you are low on mana (hard to do unless you are hitting consecrate a lot without talenting for it), AS is always going to be higher priority than judgement. While not as good as it first looks upon inspection, I believe GC is a necessity for any serious tanking spec, single or multi target. The gap is even wider on single target fights. A glyphed shield hits several times harder than a judgement.