Hah! Glad I'm not the only curiously confused one here.
Also, about Elsweyr, Hammerfell, etc. - you can't normally go to them? What are they, a tease? Background? Do you hit some invisible barrier which tells you "You've reached the edge of the world, thou n00b, turn backeth!"?
Basically that plugin removes those artificial invisible barriers, allowing you to visit the other land masses.
@DF: check your bounty if you want to know how much gold you owe for stealing