The best weapons and armor in Wicked now are those you can buy from the vendor, since you can buy a huge stack and enchant them until you get good affixes. This makes drops less exciting, something you don’t want to see in a game with diablolike loot.
Giving an extra innate affix to crafted/dropped items would make them better than items you buy from the vendor and would make it more likely to find a really exciting item that makes you say, “I want to build around that!”