Ok based on it being them limiting current systems
(which i would doubt)
I'd actually not mind, but it would cause all hell of issue with grouping.
- The "But your master X so we want you as that not Y" agruments would start and its already getting a bit need X set up!!! for dungeons at times.
- Then what about Jobs so you would get double the argument.?
- Then the FOTM group set ups leaving come classes hi and dry?
(ok to a point this could apply to DOH)
While I'm game for a change in direction that might be a loop'd'loop more then a change.
And just to throw it in..

Thiers a difference atm anyway, thier is no group crafting contenat (at least atm) where you need XYZ crafters in a group of 8 to do. So One could potentially Solo end game items atm with all DOH classes levelled.

A DoW/M cant, so its currently bias in your favour limiting it would balance it making you work as a group as the DoW/M do currentlly. :P