FFXIV has low pop and high pop servers. I’m on one of those lower pop servers in FFXIV. The economy on my server didn’t noticeably change when they implemented the world visit feature. Hell, most people don’t even really bother to server shop with marketboards, because it’s kind of a pain in the butt to do (going from server to server to check prices; there’s a website that tries to track them, but it’s rather inaccurate).
A few people optimize in this way, just like there’d be some in WoW, but it’s not at all the deathknell you seem to think.
It just sucks that I worked within the system in WoW as it was, and now I either have to fork over a stupid amount of money or deal with being completely cut off if I want to play my Alliance characters with cross-faction raiding. There has got to be a solution somehow.