True, but I also think the procedure for actually making the models is very important. What I mean by this is that FigurePrints uses a 3D printer that utilizes the armory from WOW to make the documents to do the 3d print.
(they have a video on their site explaining the process) As you said, FFXIV has this same foundation so it's possible for other companies to do this. However, it's the 3D printer specifically that makes this custom figure affordable at ~$130 by streamlining the process to easily "mass-produce" custom figures. I'm not sure of the
exact method Kotobukiya uses to make their models, but I believe they have a modeler make a prototype figure, make a negative mold from that, and then mass produce copies using the mold. Since you would need someone to personally model your character and only one final figure would be produced, it would prob cost astronomically higher (my guess is
at least $500 or more?). So unless they use/implement a similar method as FigurePrints, I can't see Kotobukiya ever doing this. Would the quality of Kotobukiya be worth the increase in price? Probably (God knows I'd want one), but I definitely wouldn't be able to afford it...