Because getting "Disassembling failed" 9 times out of 10 is just ridiculous. I can understand why it's been done with radiant crystals since those can be bought with MP now but crafting blue equipment for characters below level, say, 40, is near impossible. And the high rate of failure has shot the prices on the AH through the roof aswell.
Please make it easier to obtain crystals such as Dim ones.