You must of missed all the discussions about this topic the last time they implemented a new class/race combo. It definitely takes a lot more than a "couple hours". Items need updated to take into account the new combo, new quests are added to account for the new combo, epic quests need updated, and so on. There's a lot more that goes into making a new class/race combo than you realize. It's not as simple as just changing a few lines of code to allow it.