How does this still figure though if the same people the person buying cheap and selling TO can travel to the other servers anyway? It costs nothing to them to shop prices. If people want to pay a premium to be lazy that's fine, but intelligent buyers are shopping around now. This isn't the same as international trade since there is no infrastructure cost other than time.
The only thing I can see this affecting is people who corner markets simply because of limited availability or population. A person who used to be able to sell say.. the Taoist shirt at 30 mil because nobody on their server was organized enough to do the runs or nobody was doing the runs or nobody bothered to level the necessary skills now has to sell it cheaper because on the larger servers in their data center its a more reasonable 2 mil (or whatever it is right now, I bought mine a long time ago) .
The only thing I see this "ruining" is huge profit margins for crafters on smaller servers.
Yes this hurts your profits, but that Gil also goes farther now because those same crafters/farmers can take advantage of the cheaper prices as well.
If your goal however was only to build Gil because you like high numbers... well that does suck, but that's not economy, that's just greed.