if we always need more materials to make a moment frame (larger member size, more bolts for a rigid joint etc.), why use Moment frame when you can just release your overturning moment by using pin connection/support?
so sorry that this sound stupid...
i am sure there are benefits and necessity for moment frame which is why they were invented, i just don't know why...
may be can hold more magnitude of loads with the same number of support? (thus bigger members)?