Suppse you have 100 PvE items to craft. Now PvP is introduced, and you get a whole new set of 50 items to craft.
What is the difference to a crafter, if they simply introduced new PvE content that created real demand for a whole new set of 50 items to craft?
None.
The key is "crafters need demand". Demand for what? It doesn't matter.
If Yoshida is right in that only 20~25% of the playerbase will touch PvP, then it's actually conceivable that designing new PvE content that maybe 50% of the playerbase will play, would create much more demand (and cost less to Square Enix) than adding PvP. So if anything, Yoshida's statements is in support that "FFXIV don't need PvP".
Note the emphasis on "need" as in, "without PvP FFXIV will fail". We all know that's simply wrong. I want to emphasis that I am not saying "PvP is bad for FFXIV". I'm not saying that. Just in case some bystanding PvP fanatic gets ticked off. :3