This is an idea i have thought about for some time now. It is this and quite simple. Introduce a foreign armor crafter!
What i mean is this:
Say you have a monk from Prophecies, right? Say you want to get him/her Kurzick armor, so you need to go to Factions and play the storyline to get the armor, correct?
Well with this idea will be for a foreign armor crafter in every campaign. So instead of taking your monk to Factions and playing the story up to House Zu Heltzer.
This way you can buy the kurzick armor in the campaign in which you are in, from the foreign armor crafter and vice versa for the other campaigns.(getting NF armor in Proph, etc)
I think this idea would be very benifical and save players lots of time and effort. It would be lots more coinveinent as well.