Which they never gave up on. Advent Children and Kingsglaive. Sakaguchi was gone soon after and FF has not reached those heights again in quality. Tho I liked 12. 13 sucked. XV is blah. Kinda funny Tak and Guchi leave Square and IMO since made better RPGs than any FF game since that time. Lost Odyssey. The Last Story. Xenoblade. Then again Taks vision of Final Fantasy VII eventually got spun into its own IP. Xenogears which is easily one of the best RPGs on PS1.
I loved 12, it's second only to 7 for me. Sakaguchi said he never played much beyond the intro, due to Matsuno leaving midway through production, which I always felt was sad because Kawazu and Hiroyuki Ito turned out a great product in the end. Matsuno was another loss for Square. I'd have been quite comfortable with him as the full-time Final Fantasy boss. I've always considered FF Tactics to be a full fledged FF game alongside the numbered entries.
Unfortunately, Sakaguchi hasn't been hugely successful since he left Square, either. His last console game was almost ten years ago, and I don't really hear much about him even in the mobile space.