Actually, I played Sorrow's Furnace only a few times, not because of money farming or anything like that, but because of the thirst for quests. The quests in guild wars 1 tell stories, if you can be bothered to read the text. The same quests unfold the lore of the game. In Sorrow's Furnace I discovered things like the tome of rubicon (anyone spot that in the gw2 personal story? I only just noticed it, but GW2's storytelling is so dull I nearly missed it).
Fractals however, does not deliver me any slice of lore. It's just a place where some sort of 'testing' of some sort is going on? I really don't know. If there's any lore about the place, it's so badly delivered I don't get it. Fractals seems massively disjointed from the rest of the game whereas Sorrow's Furnace was added in and became one with the rest of the lore in it's surrounding world. So I agree with the person above; fractals is nothing more than a grinding dungeon.