Just compare the playerbase's different reactions to cash shops. While yes, there is a
demographic difference between WoW's fandom and FFXIV's, I think WoW's fandom is more vocal about the cash shop because it is yet another bad on a huge stinking pile of bad. There are so many things Blizzard is doing wrong that when a new cash shop or 6 month sub mount is announced, for many people it's the straw that broke the camel's back. Whereas Square Enix does not antagonize their customers on anywhere near the same level Blizzard does, so when new cash shop stuff is added, it irks some people but they are overall having a pleasant time with FFXIV so it's not a dealbreaker.
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This. FFXIV could be so much more than it is, but it's not actively antagonizing like WoW is.
I've seen people throw the phrase "competition will improve the game!" around a lot, but I'm personally not seeing it. Other games have been putting WoW to shame in various departments for years now, but Blizzard has never gotten off their ass and implemented their own versions to compete. For instance, so many other MMOs have housing systems and yet WoW never bothered. We'll see if 10.0 is the wakeup call but I doubt it.
This is not the same situation. These are completely different circumstances.
First, WoW is no longer the king it used to be. People checked out Warhammer and Wildstar and SWTOR and Rift for a time, but those games weren't as good as WoW. WoW had 12 million subscribers for a reason. And there is a reason why WoW barely has 2 million subscribers or less today. To say that WoW is just as appealing to people today as it was 10 years ago is denial.
Second, FFXIV is not a new MMO launching. FFXIV has been out for several years. FFXIV's recent rise in popularity is not people getting hyped for a fad, but people waking up and realizing that there is a good alternative replacement. If WoW was still good enough to have 12 million subscribers and FFXIV was launching today, it'd just be the same story as all of the other supposed "WoW killers" that came before. Clearly that is not the case.