I've been finding that there's a cycle to the holy paladin changes we've seen in Cataclysm. The latest bug with Conviction serves as the perfect example. Conviction's 9% extra healing wasn't being applied to our heals on other players, and so our healing potency was less than advertised. Holy paladins were still relatively good, even with this bug still around. Top guilds have been using holy paladins as their go-to healers, and our toolbox is diverse enough to handle what any dungeon boss can throw at us.
The fact remained that Conviction was broken, and it's not good for business when you have serious bugs affecting a class. The developers quickly hotfixed the talent, and holy paladins were suddenly seeing a 9% increase in outbound healing. A class that was already good just got better, and not by any small amount. In order to prevent us from become too powerful, Walk in the Light was quickly nerfed.