Many of your reasons may be invalid since Blizz might mix up the whole system with current classes. E.g. an additional spec for every class (except druids). Or possibly let healers use non-int gear. The current problem with a mail user is that would put LW up to 6 classes that armor is made for, while Tailoring and BS have 3 each (although LW can only make gear and leg enchants vs bags/leg enchants for tailoring and belt buckle/weapon for BS).