Personally, I don't really believe in that theory, games are made by teams, sometimes huge teams and that makes it even harder to convey the concepts without changes or alterations. Also, it is not like FF was consistent even back then, does FF7 feel like FF5 or does FF6 feel like FF1? To me, no.

Speaking of focus group-tests, FFXIII wasn't focus tested from what i know or they test it but they couldn't adjust the game based on feedback because they had to release it as soon as possible before it became a vaporware project.

Do you want an SE game that used focus group feedbacks, it is a portable game called Bravely Default, the game that people claim it carries FF's magic/soul/etc and got high user rating because it felt like NES or SNES RPG. Square add a survey contest now for sequel with three questions: "what jobs do you want in a sequel", "what plot points do you want us to cover in a sequel or spinoff", and "what merch do you want". On the other hand, A big budget console vaporware like VersusXIII is an ARPG based on fictional world that is actually "remodeled" after real world cities such as Tokyo Shinjiku, Venice and so on, as huge fan of Modern, Sci-fi and oriental JRPGs, i can't remember any JRPG did this, if there is then it is probably one or two JRPGs.

In general, I don't think JP portable devs are in better situation, many of their games are spiritual sequels, hunting and quests games, Moe/anime games, remakes, ports, homage and crossovers. Some of them even stopped releasing on portables in favor GREE or web browser games because these devs want to target the lowest spec platforms and benefit from low development cost and risks.