A lot, if not all of this seems to be coming down to just your personal preference. You are making it sound like there can be only one kind of playstation AAA title, which is a third person action adventure. And I disagree, there can be a whole diverse portfolio of playstation games.
Just because it doesn't look like a triple A game to you doesn't mean it isn't one. I'm not here to critique how good or bad Yakuza is compared to other open world games, I'm only here to say that it has a long history with the playstation brand, and Sony acquiring Sega could make it stay that way.
Why not?
Seems to me once more that you are just talking about your personal preference. You like Street Fighter and MK more than Tekken personally. But that doesn't take away from the fact that Tekken has had a long association with the playstation brand.
Again, you aren't really into Persona and you think it wouldn't fit in well with playstation's franchises when 1. playstation doesn't have to have only one kind of major game franchise as I already said and 2. this is just you personally saying you are not into it. you aren't thinking about the brands as a whole.
The bolded part is the key here. Sackboy A Big Adventure was a launch title for Ps5 and during the seventh generation, the LittleBigPlanet series was seen as groundbreaking and unique. There never really was any other video game like it.
Well we talked about Tekken earlier and Tekken 7 just surpassed Tekken 3's record as the best selling game in the series, and there is a lot of hype for Tekken 8 right now. Meanwhile, thanks to Sony, Street Fighter 5 had a botched launch. Bandai Namco also owns the Souls series which went from being considered niche to literally their biggest launch ever at the time (Dark Souls 3). My point this whole time has been how close the publishers are to Sony. Ubisoft is bigger, but none of their IPs have had a close association with the playstation brand. None that come to mind, anyway. So to me, they should remain multiplatform.
You said that they were uninterested in being acquired or weren't in negotiations to be acquired. If it is the former, then the ship has sailed. If it is the latter, then it's not too late for Sony to negotiate.