I've just spent the last few hours of my game time killing murlocs in Hillsbrad and highborne spirits in Winterspring for two enchanting recipes with no luck in a drop. I'm assuming the Formula: Enchant Gloves - Fishing and Formula: Enchant Weapon - Icy Chill no longer drop, among other recipes like Formula: Enchant Gloves - Mining.
Needless to say, I'm pretty disappointed. I'm a person who takes his professions pretty seriously. Lately I've been spending hours of my game time farming these old-world places for jewelcrafting and enchanting recipes, just to be able to say to people one day "I have every recipe in the game". I'm disappointed that as a result of the game mechanics, I will never be able to do that.
Blizzard, would you ever consider bringing these recipes back for avid collectors like me?