All of his console games so far have been funded either by Microsoft or Nintendo and since neither party releases PlayStation games for obvious reasons... Do I really need to finish this sentence? It's pretty obvious.
The only thing that seems obvious is that he went (was forced) independent and Sony wasn't willing to foot the bill for his projects like MS/Nintendo were.
What isn't obvious to me is this supposed 'dislike' towards Sony that some claim that he has, i.e.:
People like to claim that Sakaguchi not liking Ken Kutaragi is the reason
That's fine and it honestly wouldn't surprise me, but I haven't seen any direct evidence to support that, just hearsay. There were probably quite a few smaller production companies looking at Sony to take them under their umbrella post-PS2 and Sony has a storied history of not only supporting studios like these, but empowering the JRPG genre. A lot changed last gen, as we all know. The Western market exploded, Sony took a damaging sucker-punch from the PS3 reveal/pricing, and I have no doubt that a shit load of plans changed due to that.
The extent of the damage JRPGs took in the global market because of those factors we'll never know for sure. It's entirely possible that even if PS3 continued where the PS2 left off the overall worldwide popularity of the JRPG brand would have still tanked.
Next, you point out:
Neither Sony nor 3rd party publishers have been interested in funding a (multi-plat) console RPG made by Mistwalker. And now that Mistwalker seems to be focusing on smartphone games, it seems more and more unlikely that this is going to change in the near future. Mistwalker's pretty much a victim of the lack of interest for JRPGs, really. There's not a huge (publisher) demand for the kind of games Mistwalker makes anymore.
I agree 100%- but for me it circles back to the assumption of why would Sakaguchi be mad at Sony for that? It's seems like a market issue in general to me.
Didn't Mistwalker also require outsourced assistance from Artoon & feelplus, on top of financial backing from MS Game Studios, in order to get Blue Dragon and Lost Odyssey made? It was a small studio carried simply by the popularity of the "From the father of Final Fantasy" hype. Unfortunately it seemed like a lot of the XBox market didn't care much for either the JRPG genre, nor the godfather of a series that had never been on a MS platform before (sans XI).
I mean, it's not like his games on the 360 or Wii set the world on fire after all of that. He struggled when he didn't have a juggernaut publisher/developer like Squaresoft behind him. He also didn't have the supporting cast of guys like Kitase, Ito, Nojima, etc. helping to carry his projects.
Sakaguchi just seems like the John Carpenter of the industry to me these past few years.
He hit his high notes during a fantastic time in the medium, rode a very successful wave and made a respectable name for himself, and time caught up with him and (continuing the surfer analogy, in honor of The Gooch) is now struggling to get up-right on his board. Now he's going where former greats go to die: the f2p cell-phone game market.
Without Square, Sakaguchi has struggled. It's that simple. He saved the company, helped build the company up, but it ultimately became his own Frankenstein monster.